Hi,
+1 to DesertEagle comment. The Heinrichs Weikamp TTL adapter will be your best bet
It turns your YS-60 into an optical TTL slave. The "TTL" bit is very important bit here, they also have the lower cost "digital slave" adapter for Sea&Sea 4 pin strobes but that's not what you want. You want the "Heinrichs Weikamp Digital TTL adapter" (P.S. the way you can also buy direct from their website it's about 90 euros shipped)
CanadianTravelAgent:
With this adapter, the YS-60 will mimic the duration/power level of BOTH the camera's built-in preflash and main flash fired. You're effectively amplifying your camera's built-in flash power by a fixed X multiplier factor. So it's not just a dumb slave. You DO get automatic TTL exposure. Think of it as a 1-to-1 translator. The adapter applies a 'sync' signal to the wire when it detects light. And when it senses the light has stopped, it applies a TTL 'quench' signal to the wire so the Sea&Sea strobe also stops illuminating immediately
The only "disadvantage" by having an all slave system I can think of is that you're using your camera's built-in flash to signal trigger the strobes, even though you're not using the built-in flash to light anything. It's a waste of a battery really and in some circumstances if you've fired at full power you'll need to wait for the camera's built-in flash to recharge, even THOUGH the external strobes are already ready to fire. But almost all underwater most digital compacts work interact in this fashion to the external strobes
Note: not all digital cameras work with the Sea&Sea strobes, because their preflash-to-main flash interval is too short for the strobes to follow through. VERY notably, the Olympus DSLR and micro four third cameras are not compatible. But their compacts should be fine. I would recommend that you carefully look at the Heinrichs Weikamp strobe to camera model compatibility list if you decide to go down this route
My YS-60 and YS-50 TTL/S units work perfectly with the Sea&Sea DX-2G and a Heinrichs Weikamp digital TTL adapter
Happy diving!