Rentals
Rental centers will rent out Cars, Scooters and Mountain Bikes for flexible periods of time from 3 hours to 2 days with built in extensions of a day - and penalties per hour late.
A small car 1L/1000cc comfortable for 1 or 2 people can be had for around 5,000 yen.
Regular cars range from 6,300 yen to 10,000 yen a day
People movers - vans with capacity from 6/7 to 8/10 people - range from 16,000 yen to 21,000 yen a day.
Mountain bike hire in Miyanoura +81 (0997-42-0091 and -0944) for 800 yen a day.
50cc scooters "baiku" can be hired for around 4,000 yen per day, 7,000 yen for 2 days, and 3,000 yen per day after.
Electric Vehicles like the Toyota RAV4 EV can be seen not heard creeping around but sadly aren't for rent.
By bus
A highway runs around the island's coast. Buses travel most of this outer ring around once an hour from 07:00 to 18:00, taking in the airport, the two major ports, the beaches and hot springs.
There are also infrequent buses to the entrances of the hiking trails in the island's interior: twice daily to the Arakawa trail Jomon sugi and Yakusugiland, and four times daily to Shiratani Unsuikyo.
The bus times from Miyanoura port are 08:00, 08:20, 10:00, 11:20, 13:00, 13:30, 15:30, and returns from Shiratani Unsuikyo are at 09:00, 09:30, 11:00, 12:00, 14:10, 16:00, 16:10 as of May 2009. Fares are determined by the distance traveled and are not cheap — for example, the Miyanoura–Arakawa trail head is 1,400 yen one way.
Overview
Keep in mind this is a small island with few people. Relying on buses alone to get around can limit your ability to get places quickly. Private rentals are the way to go - rent a scooter if luggage allows as the one road around the entire island takes 3 hours to circumnavigate.
English is spoken less here than the cities, so bring a dictionary!
Cash
Do yourself a favour and cash up before coming in if possible. There's an ATM at the post office, which like all other Japanese Post Office ATMs accepts foreign cards. The closest one to Miyanoura port is a 30 minute walk up the road.
By taxi
Taxis can be found at the airport and ferry ports around ferry arrival times - particularly the first arrival of the day - and are scarce at other hours.
Taxi phone numbers can be found here but they don't speak english.
From The Ferry Port
It's easy to feel a little lost when first getting off the ferry at Miyanoura port. There's just a few people, not many tourists to follow, no apparent guides to help you get on a bus, no taxi and within 15 minutes absolutely no people. Overall there are more vending machines than people walking on the street.
The ferry ports have separate landing wharves for the regular ferry, and the Toppy and Rocket companies. The regular ferry port contains some useful information pamphlets, including the complete Bus timetable with destinations in Kanji only.
Up the road out of the port 10 minute walk up the hill - take a left after you get out of one of the ferry lobbies is the Environmental Centre and a cafe - Jane Bay Cafe last I checked. The Environmental Centre seems to be a touristy library pseudo museum but is also the equivalent to a Tourist Information Desk in Yakushima.