Instructions for a good bug report are as follows:

First, before anything, check the "Known Issues" section on the description to see if your bug has already been seen by us.

Next, before posting your bug report, please enter the "showseed" command into the console (accessed using F3) and paste the output somewhere inside your bug report.
(Console output can be copied by right-clicking on a line).

Additionally, please provide a workshop link to the submarine you were using.
If you were using a vanilla submarine, provide the name of the submarine instead.