Port St Johns Grounds
Depth is the range from the top of the site to its usual maximum; "recommended cert" is the mainstream-agency level operators usually ask for, not a legal rule. Currents and visibility change daily — treat everything here as planning ranges.
Port St Johns is the sardine run's capital: the shelf narrows here, pushing the migrating shoals — and everything eating them — into a workable band close to the cliffs. June and July mornings start with a launch through the river mouth or surf, then hours of reading gannet flight lines and dolphin spray until a bait ball forms. When one does, swimmers slide in on snorkel first; scuba follows only if the ball stabilizes. Common dolphins arrive in the hundreds, copper sharks carve the sphere, gannets hit like hail, and Bryde's whales end arguments in one lunge. Blank days are part of the honest arithmetic.
The moment you come for: The highest-probability staging area for full bait-ball events
Topography: Open shelf water off the Mzimvubu River mouth; action is midwater and surface, not on the seabed
Current: The Agulhas edge, counter-currents, and cold pulses all meet here; every day is read fresh from water temperature and bird behavior.
Know before you splash
Hazards: Cold water, long rough days, surf and river-mouth launches, and feeding predators at close quarters — obey the divemaster instantly.
Conservation: Boats and swimmers work under permit conditions; crews coordinate on the radio so bait balls are not mobbed by every operator at once.
Who you'll meet
For photographers
Wide angle: ★★★★★ · Macro: ★☆☆☆☆ — editors' 1–5 rating of what this site gives each style of shooting