The Sugar Loaf Islands, off the coast of New Plymouth, are the eroded stumps of an ancient volcanic crater. Above the water you can see seven islands and several reefs. Below the surface, there are spectacular cliffs, canyons, boulder reefs and sand expanses. The "sugar" is actually bird guano.
The waters around the islands are home to at least 89 species of fish, 33 species of encrusting sponges, 28 species of bryozoans and 9 nudibranchs. The area is a mixing place for both cool and warm water species. Seals and oceanic seabirds breed here; dolphins and whales regularly pass through. The islands, both above and below water, have been protected since 1986.
Guarding the eastern end of New Plymouth's harbour is Paritutu Rock, another volcanic remnant. There's a track up the rock, beginning on the northern side. It's a scramble to the top but the views are spectacular & you can see the entire New Plymouth coastline, city, port and the Sugar Loaf Islands.
Charter companies tour the Sugar Loaf Islands, and there are diving operators who can make it possible to see the underwater sights.