You can approach the island by ferryboat or by plane.
You can find information about these possibilities on the official webpage of Langeoog.
Open this site:
Der Weg zum Ziel
Langeoog is an island, so of course you can reach it by boat! There's a ferry from Bensersil that does not depend on tides. It goes about every 2 hours and a return ticket costs 19,50 € for adults for day-trip visitors. The ticket price includes the train from the harbour to the town on Langeoog. As no cars are allowed on the island, you need to park your car in one of the large car parks in Bensersiel. For more information on the ferry please see www.schiffahrt-langeoog.de.
You also can reach Langeoog by plane - there are small machines traveling to the island from Harlesiel (near Carolinensiel). It's only not cheap, with 110 € for the return flight. For more see www.inselflieger.de.
Langeoog is a car-free island, and the only cars we saw were a few electric cars. That's very nice! There's also a so-called Inselbahn (island train) that travels between the harbour and the town which takes about 15 minutes.
Instead of cars we saw many cyclists, and there are also horse-drawn carriages. Another option to discover the island is of course by foot. It only takes a while if you want to walk to the other end as that's about 11 km from the town!