There are many types of protective pouches and most of them have great reviews. However, we do recommend that you buy one that floats. This means that if for some reason the phone falls, you don't need to worry about retrieving the phone from the bottom of the pool or the ocean. It is always floating right in front of you. These pouches tend to be a little bigger than other pouches, and they can be a little more confusing to use, so make sure that you read the reviews and directions before you use them.
We bought the Segmart 2019 Universal Floating Waterproof Phone Pouch from Amazon.com and had decent results. Just make sure to get as much air out of the pouch as possible before you seal in your phone. Also, keep in mind that pictures and video can be impacted by the water on the outside of the pouch.
We also recommend that you put your phone on its brightest setting so that you can see properly while out in the elements. If possible, test your phone while it is inside the pouch before you go into the water. You will not be able to adjust the settings as much once you are out in the open waters.
The phone also gave us a heat warning at some point during our trip. However, we are not sure if this is because of the pouch or the actual hot weather. It was probably a combination of both.
Overall it was a positive experience.