With a shore that stretches 618 miles, Connecticut is ranked 20th among U.S. states by length of coastline. Here's a list of some of the top marinas in The Constitution State.
Cedar Island Marina, Clinton
Located between a protected residential area and Hammonasset Nature Preserve, Cedar Island Marina is an excellent choice for both seasonal and transient boaters. It is consistently ranked as one of the best marinas in the state and offers full-service facilities to meet the needs of their customers. They pride themselves on offering amenities similar to a resort. They have a 60-foot heated swimming pool and whirlpool with a convenient lounge area on the deck for sunbathing. The marina also maintains waterside areas for the customer's enjoyment. They offer picnic grounds, a volleyball court, a multi-slide and climbing structure for kids. They also have a 275-seat family restaurant with a large deck overlooking the water. To keep their guests active during their stay at the marina, they offer an on-site fitness center that is open 7 days a week. They also offer regulation sports like basketball, shuffleboard, pool table, etc. Four full-time staff members are available to ensure a peaceful and safe environment. They also offer after hour fuel and docking assistance. An adult lounge room that can host private parties up to 50 people is also available in this marina.
Their service department accepts jobs ranging from boat repair, painting, and mechanical. They perform total boat restoration, engine overhaul, and minor repair work. Their technicians are experts in both vintage and modern vessels, both small and large, power and sail.
Norwalk Cove Marina, East Norwalk
A complete yachting center, Norwalk Cove Marina is conveniently located just an hour from New York City. They are a full-service marina and repair facility offering top-notch facilities and knowledgeable staff. This marina has 400 boat slips that can accommodate boats up to 138 feet in length, four marina travelifts with hauling capacity of up to 150 tons, fuel dock with high speed pumps, well-maintained floating docks, piers, and ramps, private showers and restroom facilities, Wi-Fi and cable TV, a miniature golf course, picnic and barbecue areas, a fully stocked ship store and nautical gift shop, and shuttle service.
Three Belles Marina, Niantic

Just a few miles from Interstate 95 and a few minutes from the village of Niantic, a seaside community of East Lyme, Three Belles Marina is available to serve boaters. They are a full-service marina that offers both fishing and boating grounds.
Their service department offers a ValvTect fuel dock, aluminum fabrication, shrink wrapping, a canvas shop, technical services ranging from regular maintenance to complete rebuilds, electronics, running gear, fiberglass repair, and mooring services.
As for amenities, Three Belles Marina offers a restaurant, picnic areas, and gas grills, fish cleaning stations, swimming pool, free Wi-Fi, and access cards to their electronic gate.
Their docking services include wet slips, indoor valet rack, a launch ramp, trailer storage, inactive boat storage, outdoor valet rack, mooring for vessels up to 26 feet, transient rentals, and winter yard storage. 
Portland Riverside Marina, Portland
Located on 37 acres of Portland, CT, and boasts more than a quarter-mile of frontage on the Connecticut River just across from the city of Middletown, Portland Riverside Marina offers boat sales, service, marine store, a campground, fishing, and raft racing.
They have two travel lifts rated at 12 and 35 tons, a 20-ton hydraulic trailer and a 20-ton crane, which allows them to service boats up to 50 feet in length. They offer full mechanical services including total repower of all marine engines as well as carpentry and fiberglass repairs.
This marina has 74 deep-water floating slips with water and electricity as well as a number of moorings. They have a well-stocked marine store, offering all the products you need for your boat. Other amenities include transient slips, restrooms, and a shower.  
Cedar Marina, Bridgeport
A family-owned and operated for over half a century, Cedar Marina offers 140 slips, including up to eight slips available for transients. They also offer pump-out facilities, hull and engine repair, painting, electrical and mechanical services.
During the spring and summer, they offer engine tune-ups, electronic equipment installations, gel coat repair, boat detailing, diagnosis and engine repair, outboard work, and repowering.
Their winter services include engine winterization, shrink wrapping, battery storage, out-drive services.