Keith Rose: This beach on the outskirts of Reykjavik has a large sandy beach and smaller pool connected to the sea. The special feature is that it is warmed with geothermal heat. There are large changing rooms, hot soaking pools and it is free, at least it was when I was there in 2009.
Kate Rew: Adding to Keith's description - hot water is pumped into the sea during the summer months, though apparently there are swimmers here all year round. The long thin hot tub at the top of the beach is a fantastic way to chill out among Icelanders, and there is a playground in the sand which made this fun for us all. Plus, in 2015, 5 hot dogs and buns for 10 ISK in the kiosk, which you can cook yourself on the free communal beach BBQs. Dare I admit that the sea - around 20 degrees I think - felt cold to me after 10 days in Icelands 38-40 degree hot pots? Lovely family location too - the showers and changing rooms meant my youngest had a riot, but didn't spend the day with a heap of sand in his nappy. Good for holiday dynamics.