Which ocean has an average depth of about 12,000 feet, to the nearest thousand?

Mariana trench has a depth of 11,000 meters found in pacific ocean.

Explanation:

The exact depth of the ocean floor on average is about 12,100 feet but no ocean can do deeper than this level, as the ocean floor is composed of various canyons, mounds and the abyssal hill of all sizes and the depth starts to increases with the increase of angle of slope downwards. The presence of a thermocline zone that marks the deepest oceanic water temperatures found at a depth of 1000 meters, i.e 3000 feet. The water density is governed by the presence of temperature and salinity. The hadalpelagic zone represents the deepest zone and extends to 19,700 feet at the bottom of to the very bottom at 36,070 feet. The temperature is constant at just above freezing.