Elphinstone Reef

Elphinstone is a ridge of reef barely wider than a road, running several hundred meters through open water with nothing around it but blue. Its walls drop sheer on both flanks, upholstered in soft coral and swept by fusilier rivers, while the plateaus at either end gather the traffic that matters: grey reef sharks year-round, and from October into December, oceanic whitetips that cruise the shallows and inspect divers with their pilot-fish escorts in tow. Encounters happen close and demand composure - the surface interval briefing is as important as the dive plan. Between shark passes, the reef itself would justify the trip: hanging gardens, anthias haze, Napoleon wrasse on patrol. It is the deep south's signature dive and a genuine test of drift skills.

その瞬間のために: Oceanic whitetips in fall; sheer soft-coral walls; the exposed north plateau in a running current.

地形: A long, narrow offshore ridge with plateaus at each end and walls falling far beyond recreational depth

流れ（カレント）: Current usually splits at the plateaus; drift plans change on the day and negative entries are common.

エントリー: Zodiac drops on the north or south plateau depending on current; day boats run from Marsa Alam jetties and liveaboards pass constantly.

危険生物・リスク: Strong current and open-water exposure; bold oceanic whitetips near the surface; depth temptation on walls that keep going.

保全: Shark-conduct rules exist because encounters here are close; baiting is illegal and surface loitering is discouraged.

ナイトロックス: ここでは効果的です——このエリアのプロファイルは、ナイトロックスが無減圧潜水時間を有意に延ばせる水深帯にあります（適切なトレーニングを受けていることが前提です）。