The Sugar Loaf Islands Marine Protected Area (SLIMPA) was established in 1986 to provide protection for the marine environment from fishing, oil exploration and mining. It lies between the Port Taranaki Breakwater and the Herekawea stream and overlaps on the Tapuae Marine Reserve.

There are at least 89 species of fish, 33 encrusting sponges species, 28 bryozoans and 9 nudibranchs.  The New Zealand Fur Seal also makes its home on and around these islands.

Because of the sub-tropical current flowing north and the West Auckland current going south-east the waters are home to both cooler and warm water species.

It is not uncommon to see a group of Orca travelling past in late summer.

Within SLIMPA's boundaries no commercial fishing is allowed except trolling for Kingfish and Kahawai. Individual fishers are restricted to one rod with a maximum of three hooks and set netting and long lining is banned.

Within the Tapuae Marine Reserve all marine life and natural features are protected.  This means no fishing, netting or spearfishing, and no disturbance of crayfish, kina or any marine inhabitant or objects.