You will see the lake when passing by on the little road through the park. But take the time, go around it and have a look from there. It is indeed a very nice spot, and if it's not too sunny and hot, this spot (or better the bench closer to the lake) will be a very nice place for reading and relaxing. No barbequeing, though! (but BBQ pits available nearby)
It will be hard to grab it alone, unless you have been born with the right attributes needed for this cache. If not, bring someone (or something) along that will allow you to get it. Be careful, lots of muggles possible during the daytime.