Complex sentence: It is one of three major routes for merchant shipping through the Solomon Islands; the routes are the Bougainville Strait and Indispensable Strait which link the Pacific Ocean, Solomon Sea and Coral Sea; and the Manning Strait, which links the Pacific to New Georgia Sound.
Split into simpler sentences: It is one of three major routes for merchant shipping through the Solomon Islands archipelago. The 2 others are: the Bougainville Strait and Indispensable Strait route which links the Pacific Ocean, Solomon Sea and Coral Sea; and the Manning Strait route, which links the Pacific to New Georgia Sound.