It's flat....unless you are hiking at night and walk over a prone tourist.
You can walk the beach, all the streets of San Pedro, the road south, the road north, cross the cut via the hand ferry, continue hiking north up the golf cart trail. Even when you go further north to where it's grown up on either side, there is still plenty for your eyes to see, if you are into spying on nature. No matter which trail you choose, you will pass the san pedranos along the way, almost all happy to share a conversation - for that reason alone it is worth the walk. There are plenty of interesting sites along the way. Businesses, resorts, residences, parks, the ocean. Walk early morning or late evening, it can get warm.