Yep. You just immediately killed all life in a volume larger than the ship, and since diffusion on volumes that large take time, created a plume of toxic water

Yep. You just immediately killed all life in a volume larger than the ship, and since diffusion on volumes that large take time, created a plume of toxic water that will wander for many minutes before dissolving well enough. Not a big deal on the ocean. And yeah, better than an oil spill.