How far could you swim into the water before the pressure became to great?

Question

and you have an air breather

Answer 1

If you are breathing air then the depth is limited by the effects of the gas (mostly nitrogen (79%) and oxygen (21%)).

The nitrogen would start to make you feel intoxicated at about 30m (100ft), this would worsen as depth increases.

The oxygen, on the other hand, would become toxic as depth passes about 66m (210ft). Worse than the nitrogen, the oxygen may cause a type of fit underwater which would lead to drowning.

So, with air, it is not that the pressure of the water is too much physically. It is the pressure of the gases that you breathe.

If you dive with different gases (obviously some oxygen in there), you could reach amazing depths. Deeper than 1000ft is the record. Beyond this we are limited by modern technology. Scientists are only guessing what pressure the human body can withstand.