Tracking Ocean of Doom in Page Publications digests

 Ocean of Doom was originally published in MV Features' Action War Picture Library #11:

This was reprinted in Page Publications' War in the Navy #1 with Keith Chatto's rendition of the MV Features cover:

This story was subsequently recycled by Page Publications under new Chatto covers in War in the Navy #3:

And in War at Sea #2:

I expect there are more iterations of this issue to be unearthed.