Running 3800 RPM Then Suddenly lost cycliner

I have a 2001 Sea Ray Bowrider , a few months back I was cruising at 3800 RPM when suddenly lost cylinder. I was able to continue to cruising but felt something off in the the throttle. I took it upon myself to start with replacing spark plugs and general tune up. When changing cylinder 3 spark plug I found the ground electrode was burnt off but didn't think anything of it since I was changing the plugs anyway.
The boat still would fire up but still felt like I was running with a cylinder down.
Last weekend I was cruising at 3,000 RPM and the port side engine died mid run.
When I went to look at the dipstick it had milk shake looking oil, and there was water in #3 and #5 plugs.
I did a compression check it all tested good other than 3 and 5, which were at 0. Others were around 125. While doing the compression check as it cranked... water would also shoot out of 3 and 5, so not sure if this is why it was registering at 0 psi.

I have changed oil, serviced, and winterized this boat professionally every year. It has only been in fresh water.
Any ideas what I could be looking at here?
Burnt valve? Stuck valve? Manifold? Cracked block?
Any help appreciated!

Adjacent cylinders with zero compression, water in the oil, water shooting out of the spark plug holes; blown head gasket. It's the "why" that's a bigger concern to me, as head gaskets shouldn't just blow. Have you owned this since new, and, if not, do you have records of any associated work having been done to that banks of cylinders?

You should be looking for a new engine.

Yeah, sorry to say I agree, 0 compression in 2 engines is not good.