There is no single naming authority for Antarctica because it does not fall under the sovereignty of any one nation. Individual countries with an interest in Antarctica are responsible for their own national policies on Antarctic names, as well as the authorisation and use of those names.
The New Zealand Geographic Board Ngā Pou Taunaha o Aotearoa (NZGB) has a legislative responsibility to assign, alter, discontinue and approve names in Antarctica's Ross Sea region, including undersea features.
New Zealand Gazetteer of Official Geographic Names
You can find names from Antarctica's continental shelf and the Ross Sea region in the New Zealand Gazetteer of Official Geographic Names. The Gazetteer contains official names assigned by the NZGB. However, the Gazetteer is not an exhaustive list of official names in Antarctica because the NZGB does not have exclusive jurisdiction to assign, alter, discontinue or approve names for all areas of Antartica.
SCAR Composite Gazetteer of Antarctica
The Scientific Committee on Antarctic Research (SCAR) publishes the Composite Gazetteer of Antarctica (CGA) as an international resource. It is a compilation of all existing geographic names in Antarctica, and is available as a searchable database as part of the Antarctic Spatial Data Infrastructure (AntSDI).
United States Geological Survey (USGS) Antarctic Names Database
The United States Geological Survey (USGS) Antarctic Names Database maintains a comprehensive database for names in the Antarctic continent, that have been approved by the United States Advisory Committee on Antarctic Names (US-ACAN). The USGS also publishes an online Atlas of Antarctic Research.
Australian Antarctic Division
The Australian Antarctic Division hosts a catalogue of Antarctic names from the CGA, as well as listing less formal names.