Dorset Police Marine Section has a responsibility for policing the Force's 89 miles of coastline out to the territorial limit of 12 miles. This includes the busy and popular Weymouth and Christchurch Harbours, the small fishing ports of West Bay, Lyme Regis and Swanage, and the world's second largest natural harbour at Poole, which itself has over 100 miles of coastline. The Dorset coastline represents the Maritime and Coastguards Agency's (MCA) busiest area in terms of search and rescue incidents and the Poole lifeboat is the most tasked lifeboat in the country.
There are millions of pounds worth of vessels registered in or moored at the miscellany of marinas and yacht clubs (50 in Poole alone) and anchorage areas along the coastline. There are also a great many tourists and other watersport enthusiasts who bring their own craft into the area, for example divers visiting Dorset's numerous shipwrecks, windsurfing championships and a burgeoning of watercraft users. Besides these, Poole Harbour alone boasts:
- The headquarters of the Royal National Lifeboat Institution
- Furzey Island (Europe's biggest onshore oil facility)
- Home to the world-renowned Sunseeker International Shipyard.
Two cross-channel ferry services operate from Dorset's coastline across one of the world's busiest shipping lanes to France and the Channel Islands. At the peak of the season there are 8,000 traffic movements each day in and out of Poole Harbour alone.