Boat Channel

Synonyms

Back-reef trough or tide pool; Moat; Shallow lagoon

Description

There are two types of boat channels. Artificially constructed boat channels are dug, dredged, or blasted through a reef to allow access to land or wharf facilities. Such channels are usually cut normal to the reef edge or at an oblique angle and require continual maintenance. Natural boat channels, and the ones described in classical reef literature, are depressions that run parallel to the shore and are generally associated with the back reef area of fringing reefs. Darwin ( Darwin, Charles (1809–1882) ) described an example from Mauritius as a flat space with sandy bottom, located between the outer margin of the fringing reef and the island shore, the depression being sufficiently deep to offer “a safe coasting channel for boats.”

To Darwin the reason for a boat channel was clear; a reef on a sloping surface would at first grow up some distance from the shore, and, because coral on the outer edge would grow...