Hey Christina,
Waterproof cameras fall into a few different categories: Weather-sealed, waterproof with a case, and fully waterproof
Weather-sealed camera: Cameras that when paired with a weather-sealed lens, are fine in all weather be it rain or snow but are not made for use in water.
Some examples include the 5d, 7d, and 1d series from canon, d800 and similar from Nikon, and the Fujifilm X-T series.
Waterproof with a case: these cameras need a hard or soft case to seal the camera against water. These can range from rather cheap and affordable options, like the GoPro action cameras and cases, to fully custom builds capable of housing DSLRs and cinema cameras.
Fully Waterproof: No cases needed here, these are fully waterproof. Often these cameras will be rated at various depths and may offer additional lights to allow for better pictures underwater. Some to check out are the Ricoh WG series, Olympus Tough cameras, Panasonic FT30, or the Fujifilm XP140.
Last but not least depending on how waterproof you need your camera to be, you may be able to get by with your phone. Most flagship-level phones are waterproof to some degree, usually not meant for shooting under but won't be ruined by a random splash.
Hope that helps!
- Joel Wiegand