Nature and conservation
The bluffs overlooking Horoirangi Marine Reserve are more than a dramatic landscape, they are also the source of rocks for the rugged boulder reefs below. The reefs extend offshore up to 400 m and to a depth of around 20 m.
The boulders on the upper shore, regularly moved by the waves, are mostly devoid of life. Lower down the reefs are much more stable, forming a matrix of interlocking boulders interspersed with occasional patches of bedrock.
The reefs support a typical array of animals. Shellfish, anemones, sponges and sea squirts cling to the rocks; snails, starfish and crustaceans move secretively amongst the boulders, and various fish patrol above.
Ambush starfish are unusually common in Horoirangi, and their colours provide a sharp contrast to the subdued hues of the rocks and most of the other reef species.
Brown seaweeds form a dense forest between Mackay Bluff and the dramatic rocks at Ataata Point.
Octopus moving over subtidal reef at Horoirangi Marine Reserve
A vividly coloured ambush starfish waits patiently for its prey
Hermit crabs are common on the offshore sediments
Significant increases in the abundance and size of marine species in Tasman Bay marine reserves confirm their conservation benefits. Research shows that 20 years after the Tonga Island Marine Reserve was created, there are more than seven times as many crayfish and 40 times as many blue cod over 30 centimetres.
The southern end of the marine reserve at Glenduan is a short, 12km drive from Nelson. From here you can walk along the reserve, but watch for the incoming tide and take care over the boulders, as they can be unstable and slippery. Kayaks can also be launched and retrieved—with care—across the Boulder Bank.
For larger boats, there are good launching facilities at Nelson and Mapua, before embarking on a 12km boat trip north along the outer Boulder Bank. While out on the water, keep a wary eye on the weather and sea conditions; there is little shelter along this stretch of coast and stiff sea breezes regularly occur in summer.
At the northern end of the marine reserve, and well worth the 21 km drive, is Cable Bay. Although you cannot reach the reserve from here on foot, kayaks and small boats can be launched from Cable Bay beach for a pleasant trip across to Ataata Point and into the northern sector of the reserve.
Large yellow triangles onshore mark the northern and southern boundaries; offshore buoys mark the ends and the outermost corners of the reserve. Note these markers may not always be present due to operational requirements.
Boys looking in rock pools at Horoirangi Marine Reserve
Know before you go
Remember all animals, plants, and the sea bed are totally protected.
- No fishing, netting, hand gathering, taking or killing of marine life
- No polluting, disturbance or damage of marine life or the sea bed
- No removal of any natural material from the marine reserve.