limestone karsts with rowing boats vông viêng halong bay vietnam

april asia asian bay boat boats calm cruise destination distance early emerald evergreen fishing floating forests from gulf halong heritage islands isles karst karsts landscape light limestone long middle monolithic morning national near over park photo popular rowing scenic sea seascape ship site tonkin tourism tourist towards tower travel trees tropical unesco vietnam vietnamese view village viaordf ng waters world holiday vacation attraction visitor daytrip excursion nature natural