On an especially good day at Mapu’a ‘a Vaea (Chief’s Whistles), hundreds of blowholes spurt skywards at once. Time your visit for a windy day with a strong swell, when the surf, forced up through eroded vents in the coralline limestone, jets 30m into the air. The blowhole-riddled rocks stretch for 5km along the south coast, near the village of Houma.