You only need about 1 extra atmosphere of pressure for the boiling point of water to rise to 120°C, which is available at only 10 meters below the surface of the ocean. Even with a strong safety factor, 15 meters of water is well within the depths found in many large freshwater lakes, saltwater lakes, etc.

Alternatively, you can can things in a sugar syrup bath, which can easily reach the required temperatures. /s

(To be fully clear, this is an entirely terrible idea. The pressure within the cans will still rise to 2 atmospheres, and the result is very likely to be a can bomb spraying dangerously hot, and frightfully sticky sugar syrup all over anyone foolish enough to be close.)