One Piece World Seeker has a large open world environment to traverse and knowing how to fly using Luffy's Gum Gum abilities is a must when exploring it. Luffy's ability to fly is really gliding which is achieved by him being propelled through the air at high speed so that he covers a lot of distance. To be able to perform this feat you will first have to unlock the Gum Gum Rocket ability which is found under the exploration section of your Skills menu and costs 200 Skill Points.
To use the 'Gum Gum Rocket' ability hold R1 (RB) when you grapple to a point. This will launch Luffy through the air at high speed. Although he will not be able to maintain flight there are ways that you can increase the distance which Luffy is propelled. In the exploration section of the Skills menu you will find the 'Gum Gum Rocket Flight Increase' which you can buy for 300 Skill Points and it will increase the length of Luffy's flight. Also there is the 'Gum Gum UFO' for 200 Skill Points, which lets you repeatedly press X (A) when Luffy is in the air and enable him to hover. Just like with Gum Gum Rocket, the next ability for 300 Skill Points and lets you extend the amount of time that Gum Gum UFO can be used.
It is advised that you purchase these Gum Gum abilites as soon as possible so you can take advantage of the easiest and quickest way to get around the island in One Piece World Seeker.
Check out our How to Grapple page to see how you can use Luffy's grapple abilities to reach different locations.