Bonavista is built upon sedimentary deposits of the Precambrian Age (600 million years ago). On the road between Lance Cove and Bonavista you'll find one of nature's carvings - the Dungeon. It is a circular opening in the cliff with two seaward-side channels where the sea roars through. It is approximately 300 feet across and 15 metres deep. Tidal action has created a natural beach. You can swim or go through the channels in a small punt. Many people explore the bottom and sides of the Dungeon, climbing its high cliffs looking for plentiful iron pyrite (fools' gold) embedded in the rocks.