By a lot, mostly. The liquid hydrogen eventually doesn't have enough pressure/cold enough temperature to stay liquid so it turns back to gas and most bubbles ou

By a lot, mostly. The liquid hydrogen eventually doesn't have enough pressure/cold enough temperature to stay liquid so it turns back to gas and most bubbles out of the water (with some of it reacting with Oxygen and becoming more water). It's possible if it were a "big enough" and "concentrated enough" spill it might briefly create anoxic zones where fish will die. https://en.wikipedia.org/wiki/Anoxic_waters https://en.wikipedia.org/wiki/Anoxic_waters (But humans and dumb algae accidentally do that "all the time" and the ocean does have recovery methods from anoxic waters. It's not great for the climate or the ocean, but it is mostly survivable and much more "temporary" problem than the long term effects of oil pollution.)