I think starting on Memorial Day weekend Dorchester Park has kayak rentals all summer long. I don't yet own a kayak, still feeling the "pinch" of my pricey bike...but one of these days I'll get a cheapo @ Dick's for $200-300 just to be able to take it out wherever, whenever. The rentals aren't too bad...I'm thinking $7 gives you a kayak for a few hours. They even have "double" kayaks for two for the same price...can get out with DH or kids!
We are BIGTIME fans of Dorchester...! Had a SparkRally there last year and went kayaking with RAINBOWFALLS...sounds like we need to plan another gathering there! :-)