Taking the ferry from Playa del Carmen to Cozumel?

Going to Playa del Carmen in Oct. We want to take the ferry over to Cozumel. Once we get there what should we do. We're not snorkeler's. We love hanging out the beach w/ some drinks. What is there to see? And I read about Pion Island but they only let the cruise ship people go there ???? What about renting mopeds???