How can I tweak sea-level to stop it climbing up cliffs? I have tried the alteration to fs9.cfg and have tried tweaking display settings, but nothing seems to work.
This is a fairly common problem with Scenery add-ons. I would search at the file library where I got this scenery from for a fix or update, then I would search the other big file libraries for the same... if to no avail, I'd try and contact the author - if possible.
Re. tweaking the fs9.cfg or the Scenery.cfg for that matter... I doubt you'll be able to fix it this way.