Philippines / Viasayas / Panay / Estancia
Getting to the fabled Islas Gigantes is not exactly the most documented trip, nor are directions easily available on the internet. There is good information available on the web, but it takes lots of research and there is lots of outdated information to weed through for sure. This is mostly because this island group is NOT a huge destination for tourists outside of those that live in this region of the Philippines.
Even though this archipelago is frequented by mostly locals and the more savvy travelers; it doesn't mean that you wont find international tourists and folks from Manilla here as well, because you will, specially in the summer time. Gigantes is not a secret anymore, but its not growing as a destination quite like other places in the Philippines despite being fairly close to many airports such as Roxas (being the closest) Kalibo and Caticaln (which are busy hubs for Boracay travelers) and Iloilo City, perhaps the largest travel hub in the Western Visayas region.
So getting to Panay island via any of the airports mentioned above should be your first step, and it is an easy one from Manila or Cebu. A secondary option to get to Panay is to take a fastcraft from nearby islands, if you can afford the time.
Once you find yourself on Panay, there are two major jump off points to Islas Gigantes in northern Iloilo province; the port of Carles and the Port of Estancia; both are excellent options for different reasons.
Estancia is the more popular journey, simply because boats leave there mid afternoon, as opposed to early in the morning as they do in Carles. This allows travelers to arrive via bus on the same day as opposed to doing an overnight trip or requiring a stay the previous evening in Carles.
Aside from driving yourself, land routes offer two major options; vans and busses. Generally speaking, vans get you there faster, but cost more. Busses are typically cheaper and often times more comfortable, though none of those statements are a guarantee. I have been in big, comfortable vans with few passengers and strong air conditioning, and I have also been in crowded buses with no working air conditioning, and seemingly no shocks. It is hit or miss, but if you can afford the time, busses are the way to go in my opinion. You can put your luggage down below, get your own seat, personal air conditioning vents above (like a plane) and even watch a movie during the trip.
I mentioned driving yourself above and I should address that this is NOT common. Aside from the fact that most Filipinos in the provinces do not own their own cars, as the availability of public transit is excellent; but there are almost never safe places to leave your car unattended for several days at a time.
If the van option is more attractive to you because you have a group, or are more pressed for time, you can find them waiting to snipe customers outside most bus terminals. In Iloilo City, Ceres Tours (pronounced series) is the largest and most frequent operator of trips to both Carles and Estancia. In fact, they are the same bus! You just hop off the bus 45 minutes earlier if you choose to go to Estancia.
Once you have arrived in town, take a tricycle to the fish port and find the passenger terminal building, where you will be consulted by guides and asked to pay the inexpensive terminal and environmental fees, which should add up to less than 200 pesos or 4 USD.
The tourism officers will get you onto the correct boat according to your destination of choice, and your next stop is Gigantes! Travel safe.