Not quite as picturesque as immaculately landscaped Regent's Park, but a good substitute for North Londoner's when its too hot to get on the tube. Admittedly, although you might be able to avoid the tourists, but you may have more unsavoury lake companions to contend with, from rusty shopping trollies to gangs of smoking teenagers. Despite all that, boating on Finsbury Park lake can be a lot of fun, and it's much cheaper than in the Royal Parks too. Make sure you bring enough friends to man two boats and you can race around the islands and indulge in lots of pirate-themed shenanigans. Just make sure you don't decapitate any ducks! Boats are available from noon until 7pm (weather permitting) and a row boat for four people costs just ?2.50 for half an hour.