Protect Planet Ocean is an initiative by International Union for the Conservation of Nature (IUCN) with collaboration with the United Nations Environment Programme World Conservation Monitoring Centre (UNEP- WCMC). It is concerned with marine conservation and it houses data on marine protected areas (MPAs). You can explore the globe to view MPAs, however, the data for the Pacific Islands is sparse in comparison to Protected Planet.
There is a section on tools and resources categorized into twelve sections that can be searched by resources type and/or region. The website defines MPAs, Marine Reserves and Marine World Heritage Sites and answers a series of questions about marine conservation and MPAs. There is also a section on relevant news and views on the website.