I found a hatch

I was exploring Sholazar Basin one morning when i came across a hatch on a small island (@38.7 37.2). I had to see inside it. I thought i might be able to open it with a Seaforium charge. Then i saw the numbers, “5, 9, 16, 17, 24, 43″, engraved on the side and i got a strange feeling i should leave and forget about what i found.