what mountain range separates France and Spain

That would be the Pyrenees. I've sailed past the coast where they meet the sea a few times now, and honestly, seeing those peaks rising up right from the water is a pretty incredible sight. It's a massive natural barrier that really defines the border between the two countries.

It's a rugged stretch of land for sure. Whenever I've had some downtime on land around that area, I've noticed how distinct the atmosphere is on both sides of the range. Definitely worth a visit if you ever get the chance to head over that way, the views from the higher passes are something else.