Hard to say, but depth doesn't really matter when you're getting into subs, most subs will go below 2 ft, to up to 6 or maybe 8ft, the real depth depends on how far you're willing to take your sub, in murky waters, submariners usually stay at periscope depth. You can wear special polarized sunglasses to make the water look more clearer to you, hull structure is also important, you go too deep, water pressure does its thing, enjoyment is the main thing.