Bright Cave

This guide to Bright Cave in Ha Long Bay traces the twin tunnels fishermen named long ago, Hang Toi the Dark Cave and Hang Sang the Bright Cave beside it, both carved by seawater into limestone roughly ten thousand years ago. You'll hear why the two passages diverged, Bright Cave's wide, sunlit mouth against Dark Cave's narrowing tunnel that guides now avoid entirely. Duck low as you paddle in beneath the stone at the entrance.