Ka‘ena Point Arch
This natural sea arch is on the island of Oahu. Its remoteness is a welcome relief from crowded tourist areas. There are plenty of activities for the whole family - a 3-mile hike along the coastline, early morning dolphin sightings, and exploration of a large sea cave. The arch can only be explored during low tide. As this is a secluded state park, there are no amenities available; pack water, food, and whatever else you'll need for a day trip.