For a cell phone that is There is usually a lot of salt water spray and you are generally pretty wet if there is any kind of a sea kicking up. I didn't carry my Fuji XP-60 underwater camera (honestly I forgot it) but wanted to capture some shots of the Yellowfin Tuna and Dorado (AKA: Mahi-Mahi) that we caught yesterday, fishing in the Pacific off Mexico from a San Diego based boat, so I used my iPhone 6-S Plus which is really a pretty fair camera for snapshots like this.
However, I was concerned about the salt spray and the generally wet environment. So, locking the barn door after the horse is gone, I just purchased an inexpensive "waterproof" plastic case for my iPhone to keep in my tackle bag for further adventures. I do keep the XP-60 with my fishing gear but, I had it out charging when I left my house at 2:00 AM to meet my friends for the trip. Naturally, at that time of the morning (night) I am not very competent in the inventory of my gear...
The case is advertised to be good for protecting the camera fully submerged in 20 feet (~6 meters) for up to two-hours. However, at this price (under $20 USD), I have no expectations of submerging the phone. However, I am sure that it will be good enough to protect the iPhone from the salt water spray that I experienced yesterday.
I caught the largest tuna of my party - a bit over 20 pounds. Actually, these smaller Yellowfin tuna (aka: Ahi) are better eating than the monsters.