Go to Main Street on the island and climb the rope to the Poptropica blimp.
If you are on Astro Knights, return to the kingdom of Arturus on the planet Poptropica. Your spaceship will park on top of the castle.
If you are on Time Tangled Island, use the Lab (12 o'clock) setting to return to Pendulum's Lab on Main Street.
To leave any island directly (see above), get the Haunted House card from the Poptropica Store. Unlike "Dr. Hare's Lab" or "Earth Day", entering and leaving the Haunted House will not return you to where you were, but to the island map.
I don't think you can leave an island with a horse.
On every island, the Poptropica blimp is above Main Street. To leave Nabooti Island, return to Nabooti and walk right from the Museum.
you just get in the plane
any planet
To leave, use the Poptropica blimp on Main Street. (To complete the island, see the related question.)
Wait for principal to leave then you leave
Leave the castle, enter the city, and jump up into the blimp.
You click on the boat near where you came
just leave the fair and that's that.
You can only come and go using the Blimp at Fort Ridley. However, you can leave from anywhere on Poptropica using the Haunted House card from the Poptropica store. When you enter and exit the Haunted House, you return to the Poptropica map. If you leave Astro Knights island, your spaceship parks on top of the castle. If you leave Skullduggery Island, you return to find the ship docked at Fort Ridley.
You get the card from the Poptropica store, and it appears in the Store items in your item bag. You can use it to leave an island, because it takes you to the Island map.
you dont