According to the National Geographic, any Southeast Asian adventure, whether a shorter trip or a cross-country odyssey, will likely take in some of the region’s 25,000-plus islands. You will find plenty of coral-sand bays, seaside bars and swaying palms, no matter where you go, but there is far more to see beyond the beaches.

Spanning 260 square kilometers, Cat Ba is the largest island in Vietnam’s Ha Long Bay. While many pause here for just a day en route to the group’s smaller islands, adrenaline addicts tend to stick around. The limestone karst cliffs are a climbers’ playground; Butterfly Valley, rippling with caves and overhangs, is a popular spot for deep-water soloing (bouldering without ropes over deep water). A safer yet no less spectacular alternative is hiking Ngu Lam Peak, or paddling a kayak through bio-luminescent plankton.