Nelson Commonwealth Marine Reserve is a 6,123 km2 marine protected area within Australian waters located in the Southern Ocean near the South Australia-Victoria border. The reserve was established in 2007 and is part of the South-east Commonwealth Marine Reserve Network.
The reserve spans deepwater ecosystems (below 3,000 m (9,800 ft)) and encloses geological features including plateaus, knolls, canyons and the abyssal plain. It is an important migration area for humpback, blue, fin and possibly sei whales.
The entirety of the Nelson marine reserve area is IUCN protected area category VI and is zoned as 'Special Purpose'.