Comillas' main beach is a handsome crescent of golden sand below the old town, roughly 500 metres long and backed by low dunes and green hillsides. The water here is the Atlantic-facing Cantabrian Sea — cool even in August, clear when the weather is settled, and prone to waves that make it popular with bodyboarders. There are lifeguards in summer. The beach has a couple of beach bars at either end that serve cold drinks and sandwiches.
At the eastern end of the beach, a rocky headland carries the ruins of the old cemetery of the Ermita de Santa Juliana — a Romanesque chapel fallen to ruin, its tombstones facing the sea, with views back over the bay to the university and the hills. It is one of the most atmospheric spots in Cantabria, particularly at sunset when the stone catches the light and the town below is quiet. The short scramble up to the chapel from the beach takes about ten minutes.