[3] Approximately 18,000 years ago during the Last Glacial Maximum when sea levels were over 100 metres (330 ft) lower than present day levels, the South Taranaki Bight was a coastal plain which connected the North and South Islands, featuring rivers which drained into the Cook Strait (then a harbour) to the south-east.

[4] The bight was once a calving ground for southern right whales in winter and spring and early Europeans in New Zealand called it Mothering Bay after the large number of cow-calf pairs.

[5][6] Pygmy blue whales were discovered off Cape Egmont in 2007 and the South Taranaki Bight was confirmed in 2014 as the only known feeding and foraging ground for blue whales in New Zealand, hosting a unique population of its own.

[7][8] Blue whales also frequent an area off Kahurangi Point in the nearby northern South Island.

[2] A seabed survey by the National Institute of Water and Atmospheric Research in 2023 found that the bight contained 14 rocky reefs with abundant life including "kelp forests, macroalgal meadows, and gardens of 39 species of sponge.