Photography is in essence the capture of light. Given that most underwater images are captured using artificial light, often in the form of strobes, perhaps we should consider our choice of strobe as being the single most important equipment decision we make. @Alex_Mustard and @adamhanlon discuss this and offer some guidelines for underwater photographers considering purchasing underwater lighting.
That's a very odd statement at 18:05 from someone as knowledgeable as Alex about there being only one strobe on the market currently with lithium batteries - I can name half a dozen already. Backscatter MF-1 uses a single 18650 cell, AOI Q1 and SeaFrogs SF-01 use a pair of 18650s, Weefine WF-S02/Kraken KR-S02 and WF-S05 use a 4x18650 custom pack that seems to be common with their lights, and SUPE D-MAX uses the same solution, although I don't think there's cross-compatibility between them.
Sorry forgot the word “decent” in the live conversation!