The Sea of Abaco (sometimes Abaco Sound), located in The Bahamas, is an approximately 100 kilometres (62 miles) long saltwater lagoon separating Great Abaco Island (known locally as the ‘mainland’) from a chain of barrier islands known as the Abaco Cays. Depths in the Sea of Abaco are generally a few metres, and shallow reefs and shoals can pose a serious hazard to navigation. Despite these hazards, the sea is popular with boaters and is sometimes referred to as a ‘marine highway’, offering a sheltered passage through the Abaco Islands. The majority of the largest settlements and towns in the Abaco Islands are located along the shores of the sea.