A single drop falling into water: a quick upward blip as the surface breaks, then the tiny hollow ring of the bubble collapsing. Use it for sinks, rain on a window, game item spawns, and any quiet scene that needs one small event in it.
splash: sine 800 Hz -> 1600 Hz over 50 ms, 160 ms long bubble: sine 1500 Hz -> 700 Hz over 60 ms, starting 20 ms in, at 28% level splash noise: white noise 18 ms, high-pass 2.5 kHz, very quiet envelope: 1 ms attack, 110 ms decay on the splash, 50 ms on the bubble