There are a few things you need to know if you want to go down in water in Grand Theft Auto 5 for PlayStation 4. First, make sure you have the appropriate gear. You’ll need a life jacket, swimming fins, and a mask if you want to swim. Second, be aware of the currents and make sure you stay close to shore. Finally, be careful not to get too deep or too fast. If all of these precautions are followed, you should be able to go down in water without any problems.