Closest airport - Dumaguete
The final leg for all travel to Apo island requires taking an outrigger boat (bangka) for about an hour
1) Take a flight to Dumaguete
2) Take a bus from the airport to Malatapay, Zamboanguita (this is where the bangkas leave for Apo island).
You can also take a jeepney or bus from Dumaguete that drops you at Malatapay.The fare is 20 or 25 pesos respectively.
Alternately, ask your hotel to arrange the transport. The latter is far more convenient but also more expensive.
Boat rental (2 way) it doesn't matter if you stay on the island for a day or a week. The rates are the same.
2000 pesos - small boat max 4 pax
3000 pesos - big boat max 8 pax.
Travellers may also join the boats for 300 pesos per way, note that these do not have a regular schedule so you might need to wait a little at the port in Malatapey
There is a counter at Zamboanguita pier, where you pay the environmental fee.They arrange the boat for you.
Warning : You HAVE to walk through the water to board the boat. So remember to change into your slippers (the water is stony) and either wear shorts or roll up your clothes.
The boats do not have any curtains on the sides, so assume that you will be wet within minutes of leaving. Dress accordingly and be ready to be wet, and keep all your belongings (especially camera, money and documents) in your bag. The boatman will keep your bags inside the boat in the bottom, so it is safer.
Apo is a tiny island with a small beach. the small town uses gathered rainwater as tap water. there is electricity only 3 hours a day (19-22). and there is no wifi conectivity (exept for liberty lodge, and it is strictly for hotel guests only - eating at their restaurant will not grant you access to the wifi...)
Upon arrival you will be asked to pay 100p per person island fee. this tax is taken even if you are not staying overnight.
Overall the island is very nice and the locals are extremely friendly.
Details of the island can be found here - http://expattraveller.blogspot.com/
The island is only 3 km around and 120 m high at the top of the hill, however, it is hilly.
You can walk upto the lagoon and the coral beach on the south eastern coast (through Apo village)
A steep set of stairs takes you up the hill - to the lighthouse (30 minutes trek, medium difficulty). You just have to follow the stairs up to reach it. As there is only one track, you can't get lost. You won't regret the sweat as the view is really beautiful from the top of the lighthouse.
There are a number of other treks in and around the island - they can be found listed here - http://visitapoisland.blogspot.com/
One of the Philippines' famous diving sites, Apo Island has one of the world's best known community-organized marine sanctuaries. It is home to over 650 documented species of fish and estimated to have over 400 species of corals. It is a must dive for any serious aficionado in the Philippines.
Diving and snorkeling are the main activities around the island. Resorts on and off the island typically hold diving programs for different skill levels. Instructors are commonly PADI-certified. The diving is excellent, plenty of reefs, tons of fish and turtles-amazing visibility. Keep an eye out for the Giant Trevally which is known in these waters.
There are dive shops in Apo Island:
Conservation tax of P300 is charged if diving within the sanctuary and P200 if diving outside of the sanctuary.
The sanctuary is currently closed ( as per April 2014).
Alternatively Marios Scuba Diving is an excellent alternative for the 2 mentioned diveshops above!
These rates are as of June 2009
Local women will try to sell you t-shirts and sarongs when you arrive and when you leave.
Both hotels have restaurants, Liberty's has particularly good chocolate/banana shakes. Menus are limited but what is available is pretty good. At Liberty's, the dive master will go table to table during dinner and help you arrange the next day's dives.
Outside the lodges there are several local eateries scattered throughout the village. prices are higher than in larger islands, but the meals are big and it is better to buy directly from local people.
The owner at Ronor's Guesthouse serves excellent local food and the portions are huge!
Beer and basic liquor can be bought at any store / eatery. Be aware - local "boat captains" finish their workday at about 19:00 and go get drunk and might disturb young female tourists. (they don't mean any harm and wont act violently, it just can be very annoying)
Several beach resorts at nearby towns regularly offer trips to the island, and it is more common among divers and tourists to get accommodations off Apo Island. Examples of hotels and resorts outside Apo Island are Liquid Dive Resort , Playa de Malatapay Resort and Restaurant (www.playademalatapay.com) and Thalatta Beach & Dive Resort in Maluay Zamboangita ( www.thalattaresort.com ), Bahura Resort & Spa  in Dauin and Wellbeach Dive Resort in Maluay  . Rates span from budget to splurge, with some hotels usually offering a range of activities that explore the mountains, water falls, sulfur springs and other beaches of Negros Oriental.
It is commonly thought that there are only two resorts on the island, Liberty Community lodge and Apo Island Beach Resort. However there are also homestays available.
Apo island is generally the place to get out too, Dumagete is the city to get to Apo from. Here  is a good write up on the island.
(May, 2015) For those going to Siquijor, there's sometime a boat going there directly from Apo Island. Check with Apo Island beach resort (the boat goes there and back from Coco Grove Beach Resort, Siquijor).