Hawaii is known for it's beautiful beaches but the Big Island of Hawaii is known for it's constant lava flow at the Volcano National Park.
The Volcanos in Hawaii are still active and produce lava flow into the pacific ocean. The big island has a large amount of lava rock that outnumbers the sand.
While you can't see the lava from the national park, you can explore the lava tubes where the lava once came out of. You can also see the vegetation starting to grow back from where the hot lava destroyed it years before.