Some vacationers soak up sun on beaches with white or black sand. Not far away, divers suit up for a deep dive to get up close and personal with a variety of denizens of the deep. Other people check out a surreal moonscape of hardened pitch-black lava, then hike through a lush tropical rainforest.     If this sounds like a continent-wide choice of activities, that’s because the island of Hawaii in ways resembles a miniature continent. It’s almost twice the size of the other Hawaiian Islands combined. Visitors find a miniature world that encompasses virtually every kind of landscape. Dry cactus-dotted desert lies near lush rainforests. Barren lava fields contrast with waterfalls plunging into verdant valleys. People in Hawaii Volcanoes National Park come face to face with the world’s most active volcano, Kilauea, and the largest active subaerial volcano, Mauna Loa. It has erupted a total of 33 times …