Question: How Deep Can an RC Submarine Go?
The best answer I've ever read is that an RC submarine can go as deep as you want. You just might have a little trouble getting it back. The best depth is one where you can still see and control the RC submarine.
Answer: The depth that an RC submarine can go underwater really depends on your radio system. It can go as deep as your radio signals can reach and still control the submarine. Unless specially equipped for deeper exploration, most RC submarines work best at above 25 or 30 feet in depth. A depth of 5-6 feet or less in clear water is a good operating depth for most RC submarines.
The further the submarine is from shore, the less depth it can achieve because the radio signal must travel further. Generally fresh water provides better radio transmission than salt water, thus the RC submarine can go deeper in a pool or freshwater lake than in the ocean.
Visibility is also a factor. If you can't see the submarine because it is too deep, too far away, or moving too fast, then you may have trouble knowing when it has moved out of radio range and you may need to start RC submarine recovery steps. Going deep where there is limited visibility also increases the chances of getting snagged by underwater obstructions and not being able to resurface.