Just like his strength, Hulk's stamina is also perceived to be nearly as limitless due to his body counteracting fatigue poisons that build up in his muscles during physical activity. In an enraged state, the Hulk is capable of exerting himself at peak physical capacity for several days before fatigue even begins to affect him, and was able to successfully stalemate the warrior's madness Thor (a state which temporarily enhances Thor's strength and stamina to 10 times that of his normal state).
There have been several events in the past where Hulk has not only faced extended periods of time in the oxygen-depleted depths of outer space without suffocating, but he has even spoken in these inhospitable habitats. Nick Fury theorized that the Hulk could adapt to the environment of space as an inherent property of his mutation. Nick's hypothesis has since been confirmed, since it is stated that the Hulk can adapt to any environment, even airless space. The Hulk has been on the ocean floor many times and has shown the ability to breathe underwater due to his body developing a gland which creates an oxygenated perfluorocarbon emulsion, filling his lungs and equalizing the pressure. Thus, he can breathe fluid and avoid decompression and nitrogen narcosis.
Despite his incredible repertoire, The Hulk is not invulnerable. Large doses of gas can temporarily neutralize him. However, it is not an insurmountable obstacle, since the Hulk can dissipate the gas with a mighty thunderclap. Adrenaline inhibitors can be administered via syringes of Adamantium and Vibranium, aiming to revert him into the much weaker Dr. Banner, and amplified quantities can accomplish this purpose. However, if he gets angry enough, he can nullify this effect, as he demonstrated later. The Hulk's rage can also be neutralized; certain individuals can calm the Hulk down, such as Betty Ross who have done it on several occasions. Telepaths with vast empathy potential can theoretically emulate this effect as well. Additionally, the Hulk usually doesn't achieve full strength in the first moments after his transformation unless there is a substantial and significant event that breaks Banner's restraints and triggers far superior amounts of adrenaline in his circulatory system. Since dark magic empowers the Hulk, it is not properly a weakness, but depending upon his emotional state, his incarnation, and the power magnitude of the magic manipulator, this could be a potential threat, exemplified by instances where he's been shown to be more vulnerable to enchanted weapons. Finally, he can be hurt or even killed by cosmic entities or individuals with similar extraordinary levels of power, and under some conditions, be psychically manipulated by exceptionally powerful telepaths.