This stellar public swimming pool is really easily accessible by metro, being metres outside the…read moreentrance to the Lago station. The lake itself is a few metres in another direction, with nice views back towards the Palacio Real. I did have to queue to get in but it moved pretty quickly and I thought the €4.50 entry was reasonable for a one-off given the facilities but can understand another reviewer's comments that it would get expensive to swim here regularly. Changing facilities were fairly clean (apart from someone left a discarded tampon holder in a changing cubicle...srsly) and there are ample showers and toilets. There are no lockers but there is a free cloakroom and they put your bag in a little pouch so you can't see what is hanging there. I was a bit nervous about it even though there is someone sitting by it but it was fine. In fact I also forgot to hand in some of my valuables and they were sitting with my towel for about 40 mins while I swam, so it doesn't seem to be crawling with thieves (although still be cautious of course). The pool was huge and despite most people using it just for a refreshing dip I found it very easy to do some leisurely lengths, as there's loads of space and people were behaving thoughtfully. Later I realised there is a large children's pool and another almost as big outdoor pool up some stairs, which helps explain the lack of crush. It's really impressive to have all those three pools plus an indoor one. The environment around the pool is also really pleasant, there's artificial grass to sit on (no creepy crawlies!) and there's loads of hidden bits of (real) grass on the upper levels so I think it would generally be possible to find somewhere here. Overall I think this is a great place to come to cool off in Madrid, although would recommend a weekday as I imagine weekends is very busy.