Mauna Loa lava deposits create geologic attractions August 25, 2000 Share 1 -- HILO, Hawaii -- In and around this sleepy town there are several interesting geologic formations caused by old lava flows from the nearby Mauna Loa volcano. They are worth taking the time to see. Two of these attractions are the Boiling Pots at Wailuku State Park and the Kaumana Caves.Both places can be seen in under two hours, but it is worth staying longer.The Boiling Pots are a series of giant pools in the Wailuku River just downstream from Peepee Falls.The pots are extremely dangerous to swim in because there are holes in their bottoms that can suck a person under when the water is high after a heavy rain.Still they are marvelous to look at.The pots were formed when lava flows ran down an existing river bed that already had carved pools into the ground. The lava flows simply cooled in the shape of the river pools, and when the water returned, it eroded the jagged lava into smooth rock.The Boiling Pots are a good example of "columnar jointing," which is the result of cooling lava that forms vertical cracks with five and six sides. The water pots are not only the shape of a former river pool where lava settled in but also a result of the effects of cooling lava.At the Boiling Pots there is a large grassy area with rest rooms and room to have a picnic.The Boiling Pots are about a mile and a half past Rainbow Falls -- another site worth seeing -- on Waianuenue Avenue. Waianuenue Avenue runs straight from the center of Hilo.The street can be used to access the Boiling Pots, Rainbow Falls and Kaumana Caves.The Kaumana Caves are about four miles up Kaumana Drive. Kaumana Drive veers off to the left of Waianuenue Avenue, coming out of Hilo.The caves are on the right hand side of the road, and from the small parking lot look like a depression in the ground and nothing more.There is a cement stairway leading down to the caves. The caves are more accurately described as giant lava tubes.The tube on the left hand side is worth exploring for an hour or more if you are equipped with a good flashlight and closed-toed shoes.After scrambling over some rocks in a part of the cave where the ceiling comes down fairly low, the tube opens up and resembles a subway tunnel.The tube was formed by a gigantic 1881 lava flow, also from Mauna Loa.The flow cooled on the outside and formed a hard outer crust while molten lava continued to pour through the middle of the lava tube.When Mauna Loa turned off its fountain of lava to this particular tube, the remaining hot lava flowed out of the tube and left the inside hollow. Then the tube was covered on the top by more lava, dirt and vegetation, so now it is underground.The ceiling is about 50 feet high and the walls are at least 20 feet wide.The tube is very dark, so the flashlight is really a necessity.The tube seems to go on forever, and it's possible to walk quite a long way inside.