What is the outermost planet visited by Voyager 2?

The outermost planet visited by Voyager 2 was Neptune.

Voyager 2 reached Neptune on August 25, 1989, after earlier encounters with Jupiter, Saturn, and Uranus. It remains the only spacecraft ever to have visited Neptune, making the flyby one of the most important milestones in robotic planetary exploration.

The spacecraft passed about 4,950 kilometers above Neptune’s cloud tops, its closest planetary approach since leaving Earth. Voyager 2 revealed a dynamic world with powerful winds, bright cloud features, a large storm known as the Great Dark Spot, rings, and a strongly tilted and offset magnetic field.

Voyager 2 also examined Neptune’s largest moon, Triton, several hours after passing the planet. Triton displayed active-looking surface features and dark regions, including nitrogen geysers. Jupiter, Saturn, and Uranus were earlier stops in the mission, but Neptune was the final major planet in the Grand Tour.