I don't know where all the Loch's are in relation to Edinburgh, but a weekend holiday to one of them should allow you to cliff dive a bit? Albeit into cold water.
Alternatively, pay a visit to the Lake District. Lot's of lakes, and a lot of "cliffs". Best to do it when it's warm.
Yeah, because I really like jumping off a cliff into water and an area I haven't checked yet...
If you would know me in person, you'd find out that I am very cautious. Don't think you can sit back there and be like 'I am smarter than these kids, but I'm gonna wait until they screw up and tell me and THEN laugh at them.' Fuckin' biggot.