Once again, here is the link to this category:
Natural Landscape, Marine/Coastal for those who need it. For this category I'm making decisions partly based on sites I've already chosen for other categories. Here are my selections:
1. Great Barrier Reef -- the clearest shoo-in on the list; outstanding example of a tropical coral reef
2. Puerto-Princesa Subterranean River -- outstanding habitat from mountain to sea, with an underground river, in the Philippine archipelago
3. Te Waipaonamu -- outstanding fjords and glaciated landscapes in the southern hemisphere
4. West Norwegian Fjords -- classic example of fjords, among the world's longest and deepest, from the northern hemisphere
5. Gulf of California -- great biodiversity (almost 40% of the world's total marine mammal species) in this narrow gulf in dry, southwestern North America
6. Socotra Archipelago -- outstanding endemic flora and fauna on this island group near the Arabian Peninsula
7. Ibiza -- mixed site with representative Mediterranean marine and bird life; I might actually use this in place of Gulf of Porto which I'd originally thought to use to represent Mediterranean flora and fauna (it's really not just a party island; there's a lot more nature for those who look for it)
8. Peninsula Valdes -- representative Patagonian landscape by land; marine habitat for right whales, elephant seals, sea lions, and orcas by sea
9. Brazilian Atlantic Islands -- Atlantic rainforest off the northeast coast of Brazil, with representative marine and bird life
Solivagant:
Am genuinely interested in how people chose/chose between the "marine rocks"
I chose based on regions. Brazil Atlantic covers a unique area of land/sea near the tropics in Brazil. I'm in favor of New Zealand's Sub-Antarctic Islands to represent bird life and marine life representative of the Southern Ocean (they're further south than Gough), but I'd love to hear other opinions about why alternative sites might be better to represent that region. As I think you mentioned in another thread, we unfortunately don't have South Georgia Island as a World Heritage Site, because that would be a great choice.