A Year at The Poor Knights
Another major feature is the seasonal aspect of the diving. Unlike tropical reefs, where there is little change between the seasons, temperate waters have definite seasons that herald major changes to the reef community.
As spring approaches the days get longer and the water slowly starts to warm, triggering an explosion of planktonic growth and signaling many species to spawn. This is when the invertebrate life on the walls is perhaps at its best. Blue bell tunicates appear almost overnight and blanket the walls in delicate blue while other ascidians sprout around them like lollipops on a stick. By early summer they are gone but there is always something else to fill the available space.
Summer brings with it warmer water and frenetic fish activity. Many fish are spawning and some, like the black angelfish and demoiselles, are guarding their nests against predators, including divers who get too close. Sightings of tropical visitors such as sunfish and manta rays become a regular occurrence, with even the occasional close encounter underwater.
One of the big highlights at this time of year are the giant black stingrays cruising in the archways and resting in the sand. Stingrays are very gentle creatures and can be approached safely by divers. When they are resting in the sand the best approach is from the front or slightly to the side so that the ray can clearly see you. A diver can usually get to within a metre of the ray before it swims off. In the archways stingrays are often close to the surface. Divers should try to avoid exhaling directly under a stingray as the exhaust bubbles tend to startle them. It is best to dive in small groups and keep movements to a minimum. Let the stingrays come to you. As gentle as they are it should be remembered that stingrays are wild animals and are capable of inflicting severe injuries if provoked.
As autumn approaches juvenile fish start to leave the shelter of the kelp forests. Koheru stream above the kelp in schools of similar sized fish, ready to turn in unison if they are disturbed. Emerald green juvenile demoiselles and tiny leather jackets dart back to the safety of the kelp as divers approach. Autumn is also a good time to observe the cleanerfish at work. Most cleaning stations are easily recognised by the attendant group of demoiselles hovering expectantly. Look closely and you will usually see a tiny cleaner wrasse darting from one fish to another, nipping at fins and inspecting gill openings for parasites.
Winter brings the best visibility, sometimes exceeding 40m. This is the time of year to enjoy the sheer beauty and grandeur of diving at the Poor knights. The low angle of the afternoon sun penetrates the dark recesses of Rikoriko cave, illuminating the cathedral like rock structures and giving divers a chance to appreciate its vastness. Other sites, like Long Cave on the eastern side of Aorangi , offer almost unlimited visibility, sometimes in excess of 60m. There is still plenty of fish activity as some species begin their spawning and others prepare for the arrival of spring.