I mean it better to say, I dive! If you want to use “Do” later, then simply add “Do” before a verb. When using the phrase ‘do’, the only time it’s necessary to add ‘do’ is if you have highlighted the verb, e.g. “always refer to all adjectives (e.g. the letter ‘do’ in the English language). someone says “You don’t dive” and you wants to correct them “I do dive” or if the activity is noun, e.g. ‘I do painting’ (although, ‘I paint paintings’ would be preferred).