Where is this in Stresa? It's the water lily pond in the gardens of the Grand Hotel des Iles Borromees. The small pond is stocked with multicolored carp imported from Japan, and the entire pond and area surrounding it is a carefully balanced ecosystem where water, plants, and animals exist together in perfect harmony.
If you like gardens, don't miss a stroll through the park at the five-star Borromees. It's open to the public, just enter from the main driveway at the left side of the hotel.
But if you really like gardens, do your homework first; there's a lot of interesting information and statistics about the garden on the hotel website. They are rightly quite proud of the garden; some trees and features were here even before the hotel was built in 1863 and have been incorporated into the design. The rest is constantly evolving, with the seasons and the years.
Read about it, and then stroll, sit on one of the benches, and enjoy.