Today was an unexpectedly eventful day! Although I was on the afternoon deep diving team, I joined the morning team on the boat to test out the 360-degree camera system. I’ll report more on that tomorrow, after I have a chance to review the footage and stitch it all together. However, from what I saw while it was deployed, I’m cautiously optimistic! But having an extra body (me) in the boat on the morning shift meant we needed to juggle things around a bit. The Hi’ialakai launches boats by lowering them into the water using a crane. There is a limit of how much weight can be loaded into the boat for this to happen, and by the time you add up all the divers and their rebreathers and bailout cylinders, we often come close to that limit.
Nevertheless, we managed to sort it all out, and we managed to make the mid-day swap successfully after the morning dive tam completed their decompression, then it was our turn to go diving. As is always the case for these kinds of dives, there is a standard set of items we need to check on our dive gear before we take the plunge. This usually takes about 15-20 minutes, during which we become increasingly anxious to get in the water — to get the weith off our backs, get out of the hot sun and rocking boat, and most importantly, get on with the dive!
Once in the water, our deep dive began with a wholly unexpected visitor: a Hawaiian Stingray (Dasyatis lata) met us on the way down. This species is not uncommon in Hawaii, and we often see them. But invariably we see the flat against the bottom of the sea, usually over sand, and sometimes even partially buried in the sand. This one, however, came straight up to us more than a hundred feet (30 m) off the bottom, up in blue water! None of us had ever seen this behavior for this species before, and we were more than a bit surprised!
But the most exciting encounter by far (for me, at least) happened soon after we reached the bottom at a depth of about 280 feet (85 m). Jason Leonard focused on completing his fish survey, while Dan Wagner followed with benthic habitat photographs and Brian Greene set out in search of certain target fish species needed for various research projects. Off in the distance, I saw the faint outline of a shark, which I at first assumed was a Galapagos shark (Carcharhinus galapagensis), the most common shark species we see here. However as it came towards me out of the gloom, I could see it had an enormously long tail — the unmistakable characteristic of a Thresher Shark (Alopias sp.)! I din’t get a good enough look at it to confirm which species it was, but I was excited nevertheless. I’ve only seen sharks on a few occasions before, and always down deep. They tend to be very wary sharks, and this one was no exception. Although my encounter was brief, it is already the highlight of my trip! So far, anyway…