Quote Originally Posted by Jabare View Post
Since when can Hulk breathe underwater?

Marvel’s got to leave Namor something
https://marvel.fandom.com/wiki/Bruce..._Vol_1_138-158

Underwater Breathing: The Hulk has been on the ocean floor a number of times. The Hulk is able to breathe due to his body developing a gland which creates an oxygenated perfluorocarbon emulsion which fills his lungs and equalizes the pressure.[158][169] He is therefore able to breathe fluid and avoid decompression and nitrogen narcosis.
Sources referenced are Hulk 138 and 145