The beautiful building on the water was basically a fishing hole for the monks. There is a trapdoor in the floor in which the fish may have been kept fresh. A line was connected from the fishing house to the monastery kitchen to alert the cook to get the fire started.
What's funny is that besides it being a monastery, it was so beautiful along with the scenery, that pretty much all the royals stayed there at one time or another, some, for years.
The monastery disbanded in 1542. Different people owned it along the way but pretty much everyone realized the upkeep was horrendous. It is now a public park.