On the southern part of the peninsula, within the Reykjanes Nature Preserve, lies Lake Kleifarvatn, a starkly beautiful body of water with black sand beaches. Both large and deep, it exudes an eerie atmosphere with barren, volcanic surroundings.

Best viewed from Lambstangi spit on the southern end, char fishing is available during the summer months. Be on the lookout for the resident Kleifarvatn monster, a legendary worm-shaped aquatic beast the size of a whale swimming around the lake.