[1][2][3] Raet National Park is named for the long moraine formed by the retreat of a huge glacier about 12,000 years ago, which dumped an enormous quantity of boulders, pebbles, gravel, sand and clay that it had picked up over the centuries.

[4] Pebble beaches are characteristic in areas where the material is graded by heavy seas, but in more protected areas, the moraine forms fine sandy beaches that are attractive to bathers, as occur at Hove on Tromøya and on the island of Merdø.

The coastal towns of Grimstad, Arendal and Tvedestrand offer accommodation and facilities to visitors to the park.

A very special place in Raet National Park is the small pebble island of Måen (130 m long) east of Tromøy.

In rocky areas there are forests of kelp and a wide variety of fish and invertebrates but in more protected locations, eelgrasses dominate.