I paid my first visit to Trentham Gardens in Stoke the other day. This lake is the centrepiece of the gardens, which were landscaped by the legendary Capability Brown. There used to be a big stately home here, too, but along with many others around the country it was demolished during the 20th century when it became too expensive to maintain.
Nowadays there are various family-friendly activities, including a trail around the lake which we followed with the kids. There's also a good adventure playground.