Seabrook Marina is conveniently located on Clear Lake with immediate access to the Galveston Bay with 650+ slips for sail, power, and motorboats up to 125′, including multihull and catamaran slips. Seabrook Marina provides year-round docking facilities for boaters seeking a permanent slip, as well as seasonal or overnight accommodations.e have the only large covered floating docks in the Clearlake Galveston Bay area. Our new state of the art covered floating docks will accommodate up to 60′ Power Boats with a 28′ constant vertical clearance. Proven 10 degrees cooler to protect you and your vessel from the Texas heat.