Riviera Dunes Harbor is off the Manatee River. The Manatee River flows into south Tampa Bay. Entering the river is well marked and the bridges have 41 foot clearance, the CSX railroad bridge is up most of the time. Travel up the river to red marker 24A and the harbor entrance channel is on your port side. The average depth of the river in the channel is 8 plus feet and the Riviera Dunes Harbor is 18 feet deep.