The underwater landscape
East of Tinderbox Bay, the rocky sandstone reef extends up to 100m offshore. The reef drops in a series of rock platforms to a sandy bottom at around 6m depth. To the south-west of the bay, the shore drops steeply to a sandy bottom at around 5m. There are some small caves in the reef here. Water temperatures range from a cool 8°C in winter to 20°C on a warm summer's day. Underwater visibility can be 10-15m, however spring plankton blooms, rain and storms can reduce this to 5m. The best time of the year to visit is usually during summer and autumn.
Flora - the seaweeds and sea-grasses
Tinderbox reserve has a remarkable diversity of seaweeds with over 30 species identified in a single study. Their distribution varies with depth and the degree of wave exposure. Neptune's necklace, sea-lettuce and the brown seaweed Cystophora are common on the intertidal platforms east of Tinderbox Bay. Underwater, Sargassum species, sometimes called sticky weed by divers, are abundant on the sheltered reef.
As wave action increases towards Piersons Point, strap weed, string kelp and another brown seaweed called Xiphophora are seen. The steep rocky reef to the south-west of Tinderbox Bay is covered with a variety of green and brown seaweeds. Under some conditions favourable to rapid growth, a filamentous green algae grows profusely, covering both the reef and the seaweeds. Patches of sea-grass grow in the sandy areas to the south-west and in Tinderbox Bay itself. This great diversity of plant growth provides abundant habitats for marine invertebrates and fish.
Fauna - Invertebrates and Fish
Among the diverse array of animals to be found living among the seaweeds at Tinderbox, you might be lucky to glimpse the beautiful weedy seadragon. Slow and ungainly swimmers, seadragons feed exclusively on fast moving shrimp-like prey called mysids. Though brilliantly coloured with iridescent reds and yellows, they appear to rely on stealth and camouflage among the seaweeds for both hunting and hiding from predators. Seadragons belong to a family of fish which include pipe fish and seahorses. These too can be found in the reserve. Other fish that are found in the reserve include senator fish, trachinops, toothbrush leather jackets, cardinal fish and bullseyes.
Attached to the rocky reef and the bases and stems of the seaweeds are many different invertebrate animals. These include the bryozoans (colonial filter feeders that make delicately branched or lacework homes); sponges and ascidians that pump the sea water through their internal filters, sieving out plankton; and anemones and fine, feather-like hydroids that catch and sting their prey in the same way as the coral polyps of tropical oceans. Other animals move about on the reef. Octopus and squid lie in wait for prey, hiding in the rocks or among the seaweed; crabs and shrimps scavenge for leftovers while sea-snails, sea-stars and urchins graze the luxuriant growth on the rocks. In some areas urchins have grazed the seaweeds back to bare rock. On many sections of reef urchin spines have worn hollows in the stone.