The beaches South of town can all be accessed by riding your bike on the beach. Go at least to Caribe Island resort, then North to th eVictoria house and 3 miles to town. Tsest the coldness of the Belikins as needded--and the hammocks. North of town is a little less accessible.
Tanisha Tours does an excellent job with the Lamainai trip, and although arduous it is well worth it for Mayan ruins and jungle/river tours. I left my wife at the resort and went alone.