This is for your littlest one who isn't able to participate in all of the summer activities just yet. If you have a lip on your high chair tray, pour some water in there. Add a few small toys or cups for instant entertainment and refreshment.
The potential for a lot of water on your floor is a real possibility here, so consider doing it outside on a patio or balcony, covering your floor with a splat mat or shower curtain, or just deciding this will be the day you'll mop your floor.
If you don't have a large high chair tray like this one, you could fill a serving tray and put it out on the grass in front of baby.