Depending on the water level, a nice little waterfall with seating, or if there is less water, a great place for the kids to dig in the sand and build a dam. A small path leads there, which is only completely continuous when there is little water.
But please be careful: Unfortunately there are a lot of broken glass there, as it is obviously a popular place for party parties. Take a garbage bag with you and don't necessarily let the kids run barefoot.