You wont find this on a map but if you've been on social media for Zakynthos Greece you might have seen this cave. You can only get to it via boat but its not hard to find!

If you're boating by yourself without a skipper make sure the tides are okay to anchor here - they might not be. If they aren't then you'll have to anchor on the other side to the east of the cave and swim through the large crack into the cave. I've done it both ways.

I typically come here with a skipper as its only about 50 euros to hire one for the day.

https://goo.gl/maps/cZddN1U353s5VZF38