Bowser is the final boss of the game, Super Mario Sunshine.
Sometime before the events of Super Mario Sunshine, Bowser had a son named Bowser Jr. and told him a lie that Princess Peach was his mother and that Mario is keeping her away from them. Bowser Jr. then decides to masquerade as Mario and attempt to get him locked up by polluting Isle Delfino allowing Peach to be easily captured. However, Bowser Jr. ran into difficulty due to Mario not being locked up for too long. Eventually, Bowser Jr. was forced to reveal himself to Mario and escapes with Peach to Corona Mountain. Bowser is pleased to be reunited with his "family" and decides to enjoy his vacation with them. However, Mario eventually arrives at the top of Corona Mountain ruining Bowser's "family vacation." After a long battle, Mario and F.L.U.D.D. managed to defeat Bowser and Bowser Jr. and they all fall down from the sky (except for Peach who used her parasol to gently float down). Bowser and Bowser Jr. are seen on a lone island where Bowser was forced to admit to his son that Peach isn't his mother. However, Bowser Jr. already knew this but cheers Bowser up by saying he will fight Mario again when he's older. Bowser is pleased to hear his son's response and asks to enjoy the rest of their vacation together.
- "Mario! How dare you disturb my family vacation!?"
- ― Bowser
In the final battle with Bowser, he is never fought directly but stays inside his pool filled with hazardous green water. Bowser's primary attack is his fire breath where he will commonly use to cut off Mario's path. Bowser Jr. assists Bowser in this battle by firing Bullet Bills. Bowser can also shake the large tub around causing the green water to hit Mario. In order to defeat Bowser (and Bowser Jr.), Mario must Super Ground Pound the five Super Ground Pound spots around the arena. Since the Rocket Nozzle is needed for this fight, Mario shouldn't waste any time spraying down Bowser's fire breath or knocking away Bowser Jr.'s Bullet Bills. Mario can easily rocket over the fire breath if Bowser tries to cut him off with it. After five hits, Bowser and Bowser Jr. will be defeated.