Tales from the blue lagoon
 

In Reykjavik, there's a big pool called the Blue Lagoon. It's got a health spa attached to it - the water has a lot of volcanic minerals in it which are meant to be good for your skin.

My wife and I visited a few years ago and I noticed that the water is completely opaque due to the minerals.

You literally can't see below the surface whatsoever.

I tried to convince my wife to take off her bikini under the water as there would be zero chance of being spotted until she tried to get out, but alas she was not that brave.

Has anyone else been there and had better luck than I did? :D