Choosing an Underwater Strobe
Best all-around strobe choice

The Ys-110a strobe is my first choice for a strobe. They are very small and light, and very powerful - a full stop more powerful than my old YS-110a strobe. They recycle fast, less than 1.8 seconds on full power, and almost instantly on lesser power settings. The controls are very easy to use and understand, and it is quick and simple to change batteries, and add the strobe connectors. I think they are at a sweet spot at the performance to size ratio, and power to price ratio. Cost is just $639.95Â
Automatic strobe exposure (TTL) with my compact camera

When I shoot macro with my Canon S95, Canon G12 or Olympus E-Pl2 - the Ys-01 strobe gives me good power and impeccible TTL (through-the-lens)Â functionality in a tiny size. Not to mention, the strobe couldn't be simpler to use. At only $429.95, it is a true bargain.Â
Least expensive option
The Ys-02 strobe is identical to the YS-01, except it doesn't have a target light, which really isn't that useful, and it doesn't support TTL - which means you have to set the power level yourself, which many people do anyways. It is a steal at $319.95.
Best color temp for wide-angle
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If you want to shoot wide-angle and/or behavior - think about getting the Ikelite DS-160 strobe. The warm color temp means that you'll get deep rich blues in the background when you color temp adjust your photo. In addition, the DS-160 has an ultra-fast recycle time that other strobe manufacturers just can't match. If you want that winning behavior shot, these strobes are a must. Downside is a larger size than the YS-110a strobe, and a proprietary battery pack. The price is $799.95
Most power that I can get
For stunning wide-angle shots with the sun in the background, you'll want the power of the Sea & Sea YS-250 strobes. They offer unbeatable power, and near-instand recycle time. The main drawback is their larger size - they are larger than the Ikelite DS-160 strobes - and proprietary battery pack. The cost is $1,069.95.
Strobes with a video light built-in
The Ikelite DS-161 strobe is identical to the DS-160 strobe, except it has a built-in 500 lumen video light, and costs $150 more. If you want to shoot video, in addition to shooting wide-angle and behavior, this is a cost effective way to do it. The price is $949.95.
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