These concrete balls will be 30m or about 100 feet in diameter. The water is pumped out of them, which I think means they get filled with air under high pressure. If they are 700m under water the pressure would be about 70 atmospheres. That’s about 10000 pounds per square inch!! That’s a lot! https://www.facebook.com/reel/1962932787809363/?mibextid=9drbnH&s=yWDuG2&fs=e
