July 2016 - last edited July 2018
Ok this is what helped for me,
1 you swim forward.
2 the moment you are not going forward any more, release "w" key and hit esc. key (quick, to avoid going back to much)
3 hold "w" key and hit esc, you start swimming forward again.
4 repeat from 1, takes about 30 sec to get there.
Turn down your gfx settings to the LOWEST POSSIBLE and even reduce the resolution!
This has helped me get through this * part!
After you're back out, set your gfx back to what they were....
All you have to to is a little patience. Let Irish swim a little so there will be a considerable space between you and him. Keep this space to the end.