Lost Blue Hole

East of Nassau, a near-perfect circle about thirty meters across opens in the sand at twelve meters and drops far beyond recreational range. The rim is the dive: coral heads ring the edge like a crown, nurse sharks stack up in the hollows, sometimes half a dozen deep, and schools of jacks and snappers rotate above the void. Divers typically circle the lip, drop a short way into the shaft to feel its scale, then return to the rim's fish traffic. Summer aggregations inside the hole can be dense enough to dim the light below.

您此行的高光时刻: Sheer-sided ocean blue hole, piles of nurse sharks on the rim

地形地貌: Sand plain broken by a coral-rimmed circular shaft

危险因素: The shaft invites uncontrolled depth; set limits before descending and watch gauges against the featureless walls.

高氧（Nitrox）: 在此值得使用——各潜点深度落在富氧空气（nitrox）能有效延长免减压时间的区间（前提是持有相应认证）。