If you have a boat and would like to experience the Northern part of Tampa bay, I would recommend launching at Courtney Campbell boat ramp. Keep an eye on your bottom machine or make sure that you stay in the channels. There are plenty of shallow water areas to ground your boat.
If you put in on the causeway you can hang out on anywhere along the bridges or travel North up to Safety Harbor. Another nice trip from here is to head South towards Riviera Bay, near Weedon Island, where boats have been known to collect along the sandbars. Afterward, you can grab a cold drink at any of the waterfront places in the bay. I would recommend Hula Bay or the Getaway.