Some natural proposals, all of which fill a IUCN gap:
Site: Carrizo PlainCountry: USA
TWHS: no
Description: The Carrizo Plain is a large enclosed grassland plain, approximately 50 miles (80 km) long and up to 15 miles (24 km) across, in California. It would be the only representation of the Californian shrubland known for its floral biodiversity and its superbloom. It was supposed to be included in the new American tentative list, but opposition expressed by some of the locals prevented its inclusion. Its preservation is threatened by petroleum production and grazing.
Criteria: natural
Site: South Georgia IslandCountry: UK
TWHS: no
Description: The parts of the island that are not permanently covered in snow or ice are part of the Scotia Sea Islands tundra ecoregion. In total there are 26 species of vascular plant native to South Georgia. South Georgia supports many sea birds, including albatross, a large colony of king penguins, Macaroni penguins and penguins of various other species, along with petrels, prions, shags, skuas, gulls and terns. Birds unique to the archipelago are the South Georgia shag, South Georgia pipit, and the South Georgia pintail. The seas around South Georgia have a high level of biodiversity. In a recent study (2009–2011), South Georgia has been discovered to contain highest level of biodiversity among all the ecosystems in the Southern Ocean.
Criteria: natural (although one could include the whaling sites in Grytviken to make it a mixed site)
Site: Alaka'i SwampCountry: USA
TWHS: no
Description: Alaka'i Swamp is a montane wet forest on the Hawaiian island of Kauaʻi. Although the preserve is home to alpine bogs, it is not a true swamp.It is located on a plateau near Mount Waiʻaleʻale, one of the wettest spots on Earth. It is the largest intact rainforest in Polynesia.
Criteria: natural
Site: Marquesas Archipelago Marine Reserve Country: France
TWHS: maybe (5564) (As there are no maps in the official TWHS description, I do not if the proposed mixed site with detailed description of its terrestrial nature includes the entire very extensive marine reserve)
Description: The waters surrounding the Marquesas Islands are full of marine life, including various species of sharks, large marine mammals, and sea turtles, with more still to be discovered. In 2012, a scientific expedition in Marquesas found 20 marine species that had not yet been scientifically identified. 11% of the coastal fish and 10% of the molluscs are endemic, making it a one of the most diverse biodiversity hotspot in the Pacific Ocean.
Criteria: natural