Underwater photography strobes - the right and wrong choices?

Well done on finalising it! I hope you get some pics you love - and do post them here. And, most important, have a great time!

Will you have one flash or two?

Small note on clamps - I have a number of clamps similar to the ones you linked, and a pair of Ultralight clamps that I got in a store when my luggage got delayed, and the difference is quite significant. The Ultralight clamps grip better when tightened, and slide smoothly when loosened, allowing easy and precise strobe positioning without the whole setup flopping around. Cheap arms are fine, but quality clamps are worth the extra investment - I'm planning to replace all my remaining clamps with Ultralight ones before next trip.

It's be nice to have a field report about the SF-01 strobe - I had a pair of ST-100 Pros and they were serviceable, but limited to TTL-only operation when triggered by fiber optics; I have since then sold them onwards. Hopefully the SF-01 is better in this regard.

The SF-01 flashes are out of stock and unlikely to return so I would be looking for an alternative. 

I bought the last one on Amazon. I only have 1. I'd list if I purchased two.

They still sell them on Aliexpress and elsewhere. I bought the dual sync cord to future proof myself. No point to buy 1x.

Hi, have you swimn / snorkel with a UW housing + strobes before?

My experience is that It is quite complicated to push all that gear trough the water surface. Same goes for free diving.

I think you will have plenty of light with out strobes. 

Regards, Joss