The South Sandwich Trench is a deep arcuate trench in the South Atlantic Ocean lying 100 km to the east of the South Sandwich Islands. The trench is produced by the subduction

Subduction

In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 of the southernmost portion of the South American Plate

South American Plate

The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....

 beneath the small South Sandwich Plate

South Sandwich Plate

The South Sandwich Plate or microplate is a tectonic plate bounded by the subducting South American Plate to the east, the Antarctic Plate to the south and the Scotia plate to the west.The South Sandwich Islands are located on this small plate.- References :...

. The South Sandwich Islands constitute a volcanic island arc

Island arc

An island arc is a type of archipelago composed of a chain of volcanoes which alignment is arc-shaped, and which are situated parallel and close to a boundary between two converging tectonic plates....

 which results from this active subduction. Mount Belinda

Mount Belinda

Mount Belinda is a stratovolcano located on Montagu Island, in the South Sandwich Islands of the Scotia Sea. A part of the British Overseas Territory, the South Georgia and the South Sandwich Islands, it is considered the only active volcano in the United Kingdom.Belinda was inactive until late...

 on Montagu Island

Montagu Island

Montagu Island is the largest of the South Sandwich Islands, located in the Weddell Sea off the coast of Antarctica. It is a part of the British Overseas Territory, the South Georgia and the South Sandwich Islands and has the only active volcano in the United Kingdom...

 is an active volcano

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

.

It is the deepest trench

Oceanic trench

The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor....

 of the Southern Atlantic Ocean, and the second deepest of the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, after the Puerto Rico Trench

Puerto Rico Trench

The Puerto Rico Trench is an oceanic trench located on the boundary between the Caribbean Sea and the Atlantic Ocean. The trench is associated with a complex transition between the subduction zone to the south along the Lesser Antilles island arc and the major transform fault zone or plate boundary...

.

The trench is 965 km long and has a maximum depth of 8,428 metres below sea level. This location, at 55°40'S, 025°55'W, is called Meteor Deep. It is 122 km northeast of Zavodovski Island

Zavodovski Island

Zavodovski Island is an uninhabited volcanic island in the Traversay Islands group of the South Sandwich Islands. It lies southeast of South Georgia Island...

.

The southernmost portion of the South Sandwich Trench reaches south of 60°S and therefore into the Southern Ocean

Southern Ocean

The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...

, thereby containing the maximum depth of that Ocean at 60°00'S, 024°W, with a depth of 7,235 meters.