Bottom Depth Range: 65-315 feet (20-96 meters)
Sonnier Banks (formerly known as Three Hickey Rocks and Candy Mountain) is located approximately 42 km (26 mi) north northeast of McGrail Bank, and 120 km (74 mi) northeast of East Flower Garden Bank. Like Stetson Bank, it is a mid-shelf bank made of uplifted siltstone and claystone.
There are eight separate peaks associated with this salt dome. Each is a nearly conical feature formed of uplifted sandstone, claystone, and siltstone and rising up to 30 m (98 ft) from the surrounding sea floor. Two of the peaks are within recreational diving depths.
This fragile substrate has been impacted by anchoring and hurricanes. In fact, Sonnier Banks sustained severe damage during the passage of Hurricanes Katrina and Rita in 2005. It has been suggested that the level of damage from the hurricanes was directly related to earlier weakening of the substrate by chronic anchoring from vessels visiting the bank for diving and fishing activities.
The reef crests of Sonnier Banks, like Stetson Bank, are characterized as coral communities featuring fire coral, sponges and algae, as well as the invasive species, Tubastraea coccinea. Deeper habitats contain extensive mesophotic communities.
A video of Sonnier Banks taken during ROV (remotely operated vehicle) and manned submersible explorations is available on our Northwest Banks Videos page.