Mat Chau in February

Twenty divers turned up for a post Chinese New Year Saturday dive tripdeparting from the Aberdeen Boat Club (ABC) at 9:30 am. Such a good turn out was apparently due to claims of, "10 m visibility at 16 m depth and 5 m viz. at 25 m depth" reported by divers from the previous Saturday's ABC outing. The dive trip was truly multinational in nature with representatives from Germany, Hong Kong, Italy, Japan and United Kingdom.

The first dive involved an exploratory dive in rather exposed waters at one of four isolated pinnacles known as Oliver Shoals, located due south of Stanley, Hong Kong Island. A fresh northeasterly wind had stirred up slightly choppy seas and combined with a southerly moving tide to produce a surface current of about 0.3 knots. Dive Marshal Mike Belshaw selected and instructed two divers, namely Robert Christie and Mark Kelly to undertake the first dive with the orders to, "carry on diving or surface after 10 minutes if the dive was undiveable." At the first attempt to complete the task those onboard were treated to a performance display of Robert's new'Scubapro Twin Speed Fins'. According to the maker's  advertising blurb these fins, "exceed today's traditional fin performance by 30%." Despite the scientific advances of these fins they were nevertheless unable to propel their Robert at anything like the speeds required to reach the deployed marker buoy; the twin speeds presumably being 'slow' or 'just moving'. The divers soon had to increase their efforts just to catch hold of the 100 m  safety line trailing from the rear of the dive boat. With everybody on board making a mental note to avoid buying a pair of these floppy Scubapro 'Twin Speeds' the diving duo repeated the dive after our boat was redeployed slightly upstream of the marker buoy. Finally,this second dive attempt was aborted after the intrepid divers apparently failed to reach the bottom in the 10 minutes of time allotted to them. The reason given for the abort was, "the current was too strong and the viz was crap."

Brian Darvell, the deputy Dive Marshal asked me if I had any suggestions for an alternative dive site. I suggested, given the prevailing brisk northeasterly wind, which was freshening, that Mat Chau, west of PoToi might be a good choice. The boat duly anchored at this southwestern tip of Mat Chau  in moderately calm  conditions next to a sampan, fishing with hand-lines, also enjoying the sheltered conditions.

Figure1. Mat Chau in fore ground and Po Toi in background.

Two dives were then conducted by nearly everybody on board; at least all  those divers who could tolerate the rather chilly conditions i.e. 16°C water temperature. Divers, who kept to the southwestern tip,encountered a superb soft coral garden at 16 to 25 m which enjoyed about 2-3 m visibility. Numerous and sizable, orange fans, white, red and brown whips, and many red, orange, purple and white soft corals were found attached to large rocks and boulders. Some of the whips had colonies of pinkish-white anemonies attached. Banded coral shrimps, sea cucumbers, feather stars, octopi, Yellow hawkfish, Zebralion-fish, various scorpionfishes, and displays of courting Pearlspot damselfishes (Chromis notata) were also observed by most divers. A good-sized Greasy grouper (Epinephelus coioides) was seen by a few and also a Crocodile fish. Brian reported a head on collision with a Cannonball jellyfish, which apparently was almost as hard as its name implies. A 15 mm cuttlefish was also reported by Brian.

So  what happened to the, "10 m visibility at 16 m depth and 5 m viz.at 25 m depth" reported from the previous week. Well, during thecourse of a week the tidal cycle moves from 'Springs' to 'Neaps'. So next time you hear stories of great viz from the previous weekend remember it's probably already too late to repeat the dive in the coming weekend, but then there is always the prospect of the following weekend.