I am probably too late to weigh in on this. First, I have been the whole route, starting with a Light & Motion Tetra 5050, going to an Olympus SP350, graduating? to a Nikon D300 in a Subal and now using an Olympus E-M5 in a Nauticam housing. Have used various Inon and Sea and Sea strobes with a plethora of TTL devices. Just got back from the Solomon's and a photography trip where the majority of the people were shooting Olympus PEN's.
Based on my experience and the experience of others, the most overlooked flash in the world (and dissed regularly) is the Olympus UFL-2. The regular comments are; big, clunky, only uses 2 AA batteries - can't be any good. These comments absolutely must come from people who have never used them with a PEN or the E-M5. This strobe is designed for those cameras and communicates via "radio". This is a complete system that even Olympus does a lousy job of promoting.I have heard of many instances where a retailer talks customers out of the UFL-2.
It requires the use of the Olympus fiber optic cable. I use them on 5" arms on a Nauticam tray set about lens level, shooting manual, 1/125 and usually F20 or F22. The lighting is always perfect for macro subjects. I now only worry about the subject and never the technicalities of the equipment and my results show it. The only thing you need to know about this flash is the RC mode must be turned on on the flash and on the camera. Arms should be short as possible and simple. You see many octopus-looking arrangements that guarantee you will spend more time messing with your lights than you will taking good pictures.
For WA. forget lighting. Shoot shutter priority, boost the ISO and correct the white balance later (Photoshop, Lightroom or iPhoto). If you don't want to bother with post work, the underwater mode in the Olympus cameras may just do it for you. The end result will be zero backscatter. Unless you have lighting the size of a truck, strobes typically are worthless beyond 2' anyway. Effective distance of strobes on land and in the water seems to be the best kept secret in the photography world - reference the thousands of flashes witnessed at rock concerts when the lights are turned out. Also remember that what underwater strobes (read not Sola's) illuminate best is backscatter.
My wife uses 2) Sola 2000's for stills. The results are excellent. No backscatter, soft and warm photos. If a subject is outside the range of the lights, no worries, the camera is set up for a more "natural" photograph. Again, boost the ISO (1000+?). Use program mode or shutter priority. You will get great pictures with no hassle. I mount a Sola on top of my EM-5 primarily for videos and the results are great. I am still using strobes ( 2 UFL-2's), primarily because after years of fighting (and it is fighting) with lighting, I am thrilled to look in the monitor and see a well lit shot every time.
Anyway, for the Galapagos you are going to be concerned with having fun, taking great pictures. Don't dwell on lighting. Keep it simple and effective or for the WA not at all.
I may or may not set off a firestorm with these comments. If you want to get the "expert" lowdown on Olympus and Sola go to www.jackandsue.com. They are spending a lot of time and effort testing Olympus and Sola and have many examples of fantastic work on their site. They are devoted to making underwater photography easy, fun and cost effective. Not words usually associated with the sport.
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