Holei Arch
Detailed Description
Holei Sea Arch on the island of Hawaii is an example of an arch forming due to differential erosion by ocean waves. In this case, the arch formed in ancient lava flows by removing rock along cracks and weaker rocks. It will not be here forever. Every day the ocean crashes against the pillar of the arch, eroding it a little more. One day, it will be gone.
Sources/Usage
Public Domain.