Waterproof binoculars often have two focus adjustments, one on each eyepiece. These individual-focus models are awkward for daytime use, but are fine for astronomy because every subject is located at infinity, requiring only one focus setting.
Even so, most people prefer to use center-focus models. These have a single focus adjustment that controls both eyepieces, as well as a "set-once-and-forget" adjustment on one eyepiece that compensates for focus differences between your right and left eyes.
In recent years, some manufacturers have sold binoculars that have no focus adjustments. These fixed-focus models are unusable for astronomy. They do not focus at infinity and provide no means to compensate for the focus variations among different people's eyes.