Big Brother

Big Brother is a lighthouse island the size of a few football pitches, alone in open sea, and every meter of its perimeter is a wall dive. The southern plateau collects grey reef sharks and passing schools of trevally; the northern end, where the Numidia's wreckage cascades, funnels current and everything that rides it. Thresher sharks come shallow at dawn along the thermocline, silky and oceanic whitetip sharks stack under moored boats in the fall, and hammerheads ghost the blue in early summer. Between shark appointments, the walls themselves are among Egypt's most luxuriant - soft coral, black coral, gorgonians in tiers. Weather sets the terms out here: on a rough week the island is simply unreachable, which is part of why it stays so good.

The moment you come for: Dawn thresher encounters; fall oceanic whitetips beneath the boats; wall growth at its most extravagant.

Topography: An offshore island's fringing walls dropping into deep water, with sloping plateaus at the north and south ends

Current: Current wraps the island and splits at the corners; plans hinge on which plateau is workable.

Entry: Zodiac drops along the walls with live pickups; moorings are limited and conditions dictate the plan daily.

Hazards: Strong current and blue-water phases; bold sharks near the surface; remoteness measured in hours from help.

Permits & rules: Marine-park fees; operators typically require Advanced Open Water and a logged-dive minimum.

Conservation: Marine-park island with landing restrictions; conduct rules for shark encounters tightened after incidents in 2018.

Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).