Press the water surface and the water leaps from that spot. Drag to turn the view and use the wheel to move closer and further away; the space bar makes it leap in the middle. There are five presets, and pressing one swaps the particle count, the speed, and the lifetime all at once.
Particles are thrown out with an initial speed and a launch angle, fall back under gravity, and have their paths unravelled by drag and turbulence. Fine particles turn to mist, hang in the air, and drift with the wind. Particles that land leave a ring behind, and the ones with speed to spare bounce back as secondary droplets.
Pick a group in the splash panel and its values appear in the panel beside it. Double-click the title in a panel header to switch how the panels are laid out.