Wessel Marine Park, in the Gulf of Carpentaria, lies offshore from the tip of the Wessel Islands to Cape Arnhem. The marine park is valued for its biodiversity and aggregations of protected species of marine turtles and seabirds. It protects the Arafura Sill, a seafloor barrier restricting movement of water into the Gulf of Carpentaria. The sill forms a transition zone for marine life, with different communities of sponges, corals and fishes on either side.

The waters surrounding the Wessel Islands are known to support some of the most diverse and species-rich environments in the North Marine Region, with coral reef biodiversity estimated to be at least 70 percent of that of the Great Barrier Reef. It also includes the soft sediment habitats of the Gulf of Carpentaria Basin, with communities dominated by echinoderms, molluscs, crustaceans and polychaetes as well as higher-order species such as sharks, tuna and snapper.

The park covers 5,908 square kilometres, and is a Habitat Protection Zone and Special Purpose (Trawl) zone. While some types of commercial fishing are allowed in the Habitat Protection Zone, others are restricted in order to protect important habitats. – Parks Australia

Wessel ranges from 25 to 64 metres depth, with an average depth of 54 metres. The entirety of the park (>99%) falls within the mesophotic zone (30-70 metres) [view on map].

Based on annotations from publicly available seafloor imagery (Squidle+), the five most dominant seafloor categories in this Park are:

• Shallow: macroalgae (45%), coral biota (38%), sand (6%), sponges (3%), unconsolidated hard substrata (2%)
• Mesophotic to Upper-slope: no public imagery available