Training agency
National Speleological Society Cave Diving Section
United States
7 cave courses
CDS, Cave Diving Section of the National Speleological Society, NSS CDS, NSS Cave Diving Section, NSS-CDS
The cave diving section of the US National Speleological Society, founded in 1973, which trains cave divers, publishes accident analysis reports, owns and manages several Florida cave diving sites and distributes Sheck Exley's Blueprint for Survival free of charge.
The NSS Cave Diving Section grew out of meetings of cave-diving members of the National Speleological Society in 1973, with Sheck Exley as its first chairman [1]. Its history page credits the section with Exley's 1979 book Basic Cave Diving: A Blueprint for Survival, which set out safety rules drawn from accident analysis, and with its first instructor institute in 1980 [1]. The same page records that US cave-diving deaths peaked at 26 in 1974 and later fell below five a year, which the section attributes to education [1]. The section now offers the Blueprint book as a free download [3]. Its home page describes it as the largest cave diving organisation in the United States, with a presence in 25 countries, and lists training, accident analysis, a conservation policy, the Underwater Speleology newsletter, managed properties and an instructor listing [5].
The NSS-CDS restructured its curriculum around 2019-2020. According to an account published in InDepth, the older modular ladder of Cavern, Intro to Cave and Basic Cave was replaced by a non-certification CDS Basics orientation, an Apprentice Cave course and a full Cave course, while Cavern became a stand-alone single-cylinder awareness course [7]. The section's current course pages match that structure: Single Tank Cavern Diver is not a prerequisite for cave training, Apprentice Cave Diver is Part I and Cave Diver completes the full certification, and specialities include Stage, DPV, CCR, Trimix, Advanced Sidemount, Cave Surveying and Cartography [9][11].
7 courses
Cave-related courses
As published on the organisation's own course or standards pages; the official page is the authority. Similar names elsewhere are not automatically equivalent.
| Course | Prerequisites | Scope and published limits |
|---|---|---|
| Single Tank Cavern Diver ↗Cavern · min. age 18 · checked 2026-10-14 | At least 18 years old; Open Water Diver or equivalent from a recognised agency. No minimum dive count. Nitrox may be taken concurrently but is not required. | A safety and awareness course for open-water divers using single-cylinder sport equipment: avoiding the mistakes behind cavern and cave fatalities, trim and propulsion, team diving, light use where lights are reserved for certified cavern and cave divers, staying in sight of the entrance and daylight, fauna, geology and conservation, and judging whether to pursue further overhead training.The page states no numeric depth or penetration limit. Training stays in clear sight of the entrance and daylight. Equipment includes a single cylinder of at least 1,850 litres starting gas volume. Minimum four dives and 90 minutes of cavern bottom time, generally over two days. |
| CCR Cave Diver ↗Rebreather (CCR) cave · min. age 18 · checked 2026-10-14 | At least 18; Advanced Open Water or equivalent; rebreather diver certification from a recognised agency; at least 50 logged dives; at least 25 dives and 35 hours on the same rebreather used in the course. | Described by the NSS-CDS as the closed-circuit equivalent of Apprentice Cave and Cave Diver combined, covering largely the same knowledge and skills on a closed-circuit rebreather. Many students complete the first part on open circuit.Equipment rules as published: absorbent, diluent and oxygen for 150 percent of planned dive time; open-circuit bailout of at least 150 percent of the gas needed to exit from the maximum penetration point, in two or more cylinders or one H-valve cylinder. No maximum depth stated. Generally six or more days and at least 600 minutes of bottom time. |
| DPV Cave Diver ↗Scooter (DPV) cave · min. age 18 · checked 2026-10-14 | At least 18; full Cave Diver or equivalent; at least 50 non-training cave dives after Cave Diver certification. The NSS-CDS describes Stage Cave Diver or equivalent experience as close to essential. | Managing the added risks of scooters in caves: gas reserves for a scooter failure, towing a teammate (including while sharing gas), staying on the guideline at speed, avoiding ceiling strikes, and riding in ways that limit damage. The page notes some sites ban DPVs.No numeric gas formula or depth limit is stated; the page warns that keeping twice the starting gas volume in reserve may not be enough. Generally three days and three or more dives. |
| Cave Diver ↗Full cave · checked 2026-10-14 | NSS-CDS Apprentice Cave Diver or equivalent. For planned decompression dives, certification covering oxygen-rich decompression gases and decompression procedures, which may be taken concurrently. | Part II of full NSS-CDS cave certification. Confirms Apprentice-level skills are maintained, then covers navigation with jumps and gaps, at minimum the theory of complex circuits and traverses (including the idea of a halfway point or point of no return), and applying decompression training in caves.The course page states no numeric depth, penetration or gas limits. At least 360 minutes of bottom time over at least eight dives, generally four days. |
| Apprentice Cave Diver ↗Intro cave · min. age 18 · checked 2026-10-14 | At least 18; at least 50 logged dives; Advanced Open Water Diver or equivalent; entry-level Nitrox or equivalent (may be concurrent); technical sidemount or a basics/fundamentals/essentials course from a recognised technical agency, or equivalent sidemount or backmounted doubles experience. Instructors must confirm buoyancy, trim and propulsion; those who fall short may first take the non-certification CDS Basics orientation. | Part I of the two-part path to NSS-CDS Cave Diver. Focuses on limited penetration along the main line and on emergency skills, giving supervised experience of fundamental cave skills.No numeric depth or penetration limit is stated on the course page; penetration is described as limited and along the main line. Equipment: two sidemount cylinders or manifolded doubles with at least 4,200 litres starting gas volume, primary light rated for 150 percent of dive time plus two backups. At least 360 minutes of bottom time over at least eight dives, generally four days. |
| Advanced Sidemount Diver ↗Sidemount · min. age 18 · checked 2026-10-14 | At least 18; full Cave Diver or equivalent from a widely recognised agency; at least 50 non-training cave dives after initial Cave Diver certification; several logged sidemount cave dives. | Prepares cave divers for passages so tight that one or both sidemount cylinders must be removed, for the so-called ratchet effect where a diver cannot back out of a passage, for a teammate becoming stuck in a long single-file restriction, and for gas management that differs from standard sidemount practice.No depth or penetration limits are published on the page. Equipment minimums match other NSS-CDS cave courses (starting gas volume of at least 4,200 litres, primary light rated for 150 percent of dive time, two backups). Generally two days with three or more dives. |
| Cave Surveying ↗Survey project · min. age 18 · checked 2026-10-14 | Minimum age 18; Full Cave Diver or equivalent from a widely recognised agency. | Fundamentals of underwater cave survey for cave divers of any experience level: the history of survey standards, the seven phases of a survey project, accuracy standards, team composition, tools, techniques and calculations, symbology, cartography, and copyright and publication.No limits are published on the page. Two or more dives, generally two days. The NSS-CDS lists a separate Cartography course. |
6
Providers stating this affiliation
| Provider | Where | How we know |
|---|---|---|
| Bahamas Underground | Marsh Harbour, Great Abaco Island | Provider's own website |
| Cristina Zenato | Grand Bahama | Provider's own website |
| Underworld Tulum | Tulum | Provider's own website |
| Cave Adventurers | Marianna | Provider's own website |
| Cave Country Dive Shop | High Springs | Provider's own website |
| Dive Outpost | Live Oak (near Luraville) | Provider's own website |
Further reading
Breathing Gases in Cave Diving: Why Every Cylinder Is Analysed and Labelled
A conceptual guide to the gases cave divers breathe (air, nitrox, helium mixtures, oxygen), why each cylinder is...
Cave diver training stages and terminology
Most agencies move divers from cavern to an introductory or limited cave level and then to full cave, before...
Cavern and cave diving: what is the difference
Cavern diving stays in the daylight-lit entrance area of a cave; cave diving goes beyond it. Agencies define the...
Communication and Documentation Underwater: Light, Hands, Touch, Cameras and Their Limits
How cave divers communicate without speech, using light signals, hand signals, touch contact and written notes, how...
Conservation, landowners and responsible access
How access to underwater caves depends on landowners and managers, with documented examples: Wakulla and Peacock...
Diver Propulsion Vehicles in Caves: Uses, Risks and Training
Scooters let cave divers travel much further, but distance multiplies the consequences of any failure. This article...
Environmental hazards in underwater caves
Silt, restrictions, haloclines and chemical layers, flow and siphons, floods, tannic water, depth and cold: what the...
Equipment Configurations for Cave Diving: Backmount, Sidemount and Streamlining
Why cave divers care so much about how their equipment is arranged: redundancy, access to gas, team compatibility,...
Exposure Protection in Cave Water: Wetsuits, Drysuits and Heated Undergarments
How divers lose heat in water, why long cave dives make thermal protection a planning issue even in mild water, and...
How to choose a cave instructor or training provider
Questions to ask before booking cave training: which standard applies, whether the instructor is currently...
Keeping skills current: continuing education, currency and mentoring
Most cave cards never expire, but agencies build currency into their limits and progression rules: dive within...
Lighting in Cave Diving: Primary Lights, Backups and Redundancy
Why cave divers carry several independent lights, what a burn-time or beam rating actually describes, and how light...
Navigation and Survey Instruments: Compasses, Depth and Time, Slates and Electronic Survey Devices
What cave divers use to record depth and time, take bearings and write notes, how underwater cave surveys turn those...
Rebreathers in Caves: How They Differ, the Bailout Concept and What Training Involves
Closed-circuit rebreathers let cave divers stay longer on far less gas, but they add failure modes that open-circuit...
Reels, Spools, Guidelines and Line Markers: What They Are For
The continuous guideline is the cave diver's route home. This article explains reels and spools, what guidelines are...
Specialist areas: sidemount, rebreathers, scooters, surveying and scientific diving
What cave specialities involve, what agencies require before them, and the limits they publish. Nearly all assume...
Threats to underwater caves today, and how they are protected
A dated overview of documented pressures on underwater caves: wastewater and nitrate, Tren Maya construction over...
Training, conservation and decision-making
Accident reports keep pointing back to judgement: staying within training and site rules, ending dives and rescue...
What accident analyses have found
From Sheck Exley's 1979 Blueprint for Survival to DAN's three-decade fatality review and today's NSS-CDS case...
Why overhead environments demand specialist preparation
In a cave there is no swimming straight up to air. This article explains, without instructing, how that one fact...
Basic Cave Diving: A Blueprint for Survival ↗
The founding text of accident-analysis-based cave diving safety. Each chapter opens with a real accident...
Caverns Measureless to Man ↗
Sheck Exley's own account of a life spent exploring underwater caves, illustrated with photographs and...
History of the NSS-CDS ↗
The section's own history, including equipment milestones credited to its members: line arrows, jam-proof...
NSS-CDS Accident Analysis ↗
A running list of North American cave diving incidents with downloadable committee reports (recent cases...
NSS-CDS cave courses and equipment requirements ↗
Index of NSS-CDS courses (cavern through DPV, CCR, trimix and survey). Individual course pages list...
NSS/CDS Cavern Diving Manual ↗
The NSS-CDS manual for its cavern training, sold through the section's shop. (A cavern is the part of a...
Report an Incident ↗
DAN's voluntary reporting route for diving injuries, near misses and witnessed accidents, feeding a...
Thirty years of American cave diving fatalities ↗
A review of 161 cave diving deaths reported to DAN between July 1985 and June 2015, covering training...
Sources:
[1] NSS Cave Diving Section ↗[2] NSS Cave Diving Section ↗[3] NSS Cave Diving Section ↗[4] NSS Cave Diving Section ↗[5] NSS Cave Diving Section ↗[6] NSS Cave Diving Section ↗[7] NSS Cave Diving Section ↗[8] InDepth (Global Underwater Explorers) ↗[9] NSS Cave Diving Section ↗[10] NSS Cave Diving Section ↗[11] NSS Cave Diving Section ↗[12] NSS Cave Diving Section ↗
· checked 2026-10-14
Every fact on this page, with its source (12)
| Fact | Status | Source |
|---|---|---|
| The NSS-CDS was started in 1973 by cave-diving members of the National Speleological Society, with Sheck Exley as first chairman. | Verified | [3] |
| The NSS-CDS describes itself as the largest cave diving organisation in the USA, with a presence in 25 countries.Self-description. | Verified | [1] |
| The NSS-CDS states that more than 400 divers have died in underwater caves.No date or geographic scope is given for the figure. | Verified | [1] |
| The NSS-CDS history page says cave diving deaths fell from 26 in 1974 to fewer than five a year, crediting its education efforts.Organisation's own account; the 1974 figure also appears in the Blueprint foreword, which refers to Florida. | Verified | [3] |
| The NSS-CDS Accident Analysis Committee publishes reports on individual cave diving accidents and asks divers to report incidents to DAN. | Verified | [7] |
| The NSS-CDS property management plan covers Cow Springs, Edwards Springs, Mill Creek Sink and School Sink, with site-specific access requirements.The plan states that no diving was yet permitted at Edwards Springs. | Verified | [9] |
| The NSS-CDS was started in 1973 by cave-diving members of the National Speleological Society, with Sheck Exley as first chairman. | Verified | [2] |
| Sheck Exley's Basic Cave Diving: A Blueprint for Survival was published in 1979 and the first NSS-CDS instructor institute was held in 1980 in Branford, Florida. | Verified | [2] |
| The section's history page says annual cave-diving deaths peaked at 26 in 1974 and later fell to fewer than five a year.Figure as stated by the NSS-CDS; the page does not cite a dataset or define the geographic scope. | Verified | [2] |
| The NSS-CDS describes itself as the largest cave diving organisation in the United States, with a presence in 25 countries.Self-description. | Verified | [6] |
| Around 2019-2020 the NSS-CDS replaced its Cavern / Intro to Cave / Basic Cave ladder with a non-certification CDS Basics orientation, Apprentice Cave and Cave, and made Cavern a stand-alone awareness course.Described in a 2020 magazine article written by NSS-CDS figures; the current course pages are consistent with it. | Reported | [8] |
| Single Tank Cavern Diver is not a prerequisite for, and does not count toward, NSS-CDS cave certification; Apprentice Cave Diver is Part I of the two-part path to Cave Diver. | Verified | [10] [12] |
Verified: stated by an official or primary source we opened. Reported: from a secondary source only. Sources conflict: the note gives both versions. May be out of date: the newest source we found is old.
Written in our own words from the sources above. Report a correction