Larantuka is usually reached by a three- to four-hour bus or car ride from Maumere. The comfortable Travel vans that run in other areas of Flores don't come this far, so you'll have to take the local bus. These can be an interesting cultural experience, but can also be crowded to the brim, and the drivers sometimes have interesting notions of road safety.
A bus from or to Maumere will cost about 80,000 rupiah and can be caught either at the city bus terminal or from your hotel, where you will be deposited on the side of the road with your bags. The bus terminal in Larantuka is far outside of town, and you will need a bemo to get to your hotel. Alternately, your bus may be heading for the town centre from the terminal; ask the driver.
True masochists can catch a local bus all the way to Bajawa from the Hotel Tresna. This costs about 100,000 and takes about 12 hours, give or take. It's also possible to take this bus to Ende. As with all travel in Flores, things are very fluid and you should always verify this information upon arrival.
A private car and driver from Maumere will cost between 450,000 to 500,000 rupiah to make the journey. Stops at small villages along the way are possible if you go this route.
Larantuka is connected to Adonara, Solor, and Alor island by means of ferry, which can be hailed near the local market. Schedules change very often, and it's best to check with your hotel or with a local travel agent for the most up-to-date information.
It's possible to arrange day trips to Adonara island for 100,000 and 200,000 rupiah, deepening on the captain's whims and the current price of petrol. Check with the folks at Ile Mandiri tour, or with your hotel.
Boats to Lembata island cost 25,000 rupiah and there are two or three boats on any given day, from 08:00 to midday. Scheduling is notoriously fluid, so check ahead. The Pelni ferry to Kupang leaves once every two weeks, where you can get your Indonesian visa renewed if you're in need -- this can't be done in Larantuka.
Larantuka is small but rather spread out, and walking may not be a realistic option. The usual intercity bemos are in evidence, as well as the occasional ojek driver. You can usually hire an ojek driver for the day for around 100,000 rupiah. Ask your hotel if they can arrange do it yourself motorbike hire. The going rate for this is around 70,000 a day.