Woodberry Wetlands, managed by London Wildlife Trust, is an 11-hectare site between Harringay and Stoke Newington.
Today Sir David Attenborough joined London Wildlife Trust staff and volunteers on the press day mark the opening of the reservoir to the public for the first time in 200 years.
Sir David said access to the natural world was a "birthright" and should not be regarded as a luxury.
He added: "We are part of it and if we lose contact with the natural world, you lose contact with a great source of pleasure and delight which is your birthright."
The new wetlands reserve is based in and around the early 19th Century east reservoir. Both it and the New River which feeds it are still owned by Thames Water and are a part of London's daily water supply.
London Wildlife Trust said the site had more than 13,000sq metres of reed bed and 550sq metres of hedgerow, wildflower meadows and fruit trees to attract birds, bees, butterflies and other insects.
The Wetlands is open to the public both today and tomorrow. See our event listing for details.
Not open to the public on other days then?
It's open every day. The days Hugh referred to were the 'grand opening' days. They had guides etc, whereas usually presumably a bit quieter (though there are to be regular events taking place).
Sir David Attenborough … is now the name of a boat. Rather than, Boaty McBoatface.
I think the officials have got it right and the pubic poll had it wrong!