2 Best Sights in Big Island, Hawaii

This way-out adventure explores the underbelly of the world's most active volcano via the Kazamura Lava Tube system. The world's longest lava tube system—more than 40 miles long, with sections up to 80 feet wide and 80 feet tall—is 500 to 700 years old and filled with bizarre lava formations and mind-blowing colors. Tours, customized to groups' interests and skill levels, focus on conservation and education and take visitors through beautiful lava caves unlike any others in the world. The tours are by reservation only and are well worth the extra detour (about 40 minutes off the main highway) and planning. Equipment is included. When you make your reservation, you will be given detailed directions to the location.

Thanks to Hilo's abundant rainfall, this lava tube is lush with plant life. Concrete stairs lead down to the 2½-mile-long tube, which has no lighted areas. The ground is uneven and damp, so wear sturdy shoes, bring a flashlight, and explore as far as you dare to go. There are restrooms and a covered picnic table at the cave, and parking across the street. Heed all warning signs when entering the caves.