The Islets of Yav are approximately two good weeks sailing from the nearest port. This entails leaving from the rather remote fishing and whaling village of Lemogue. Finding such long passage there will be difficult and probably not cheap. Most fishing ships are smaller and not suited to long trips. Whaling ships are larger and better suited, but are either moored in the off season, with their crews gone fishing, or they are away during the whaling season and not really interested in playing hero ferry.
Lemogue - a salty village
Lemogue is an insular fishing community of a few hundred individuals, swelling to almost 2000 at the peak of whaling season. They are very local, distrustful of outsiders, and are used to taking matters into their own hands, and not looking for protection from the army, or the King's justice. Those looking for find passage will need not just gold, but will have to earn the respect of anyone who owns a ship. This is a low man's respect, and requires calloused hands, a willingness to do menial labor aboard a ship, and to follow directions without question. In other times, Lemogue has been known to shelter a pirate or two. Good Kingsmen aren't always given the warmest welcome. They are a crusty and suspicious lot.
The Fishing Boat Option - the adventurers-upon-return hire a fishing boat to ferry them to the islets. The boat is only large enough to carry ten people, plus supplies for the trip. Accommodations are dismal, and many people will have to sleep on the deck of the boat. The boat is also only moderately seaworthy, and can be easily damaged by storms, large marine wildlife, or it can be easily taken by other larger ships. It also takes longer, as the ship's round hull and sails are made for fishing, not quick dashes across the ocean.
The Whaler Option - the adventurers-upon-return hire/gain passage on one of the Lemogue whalers. These two masted sailing ships can chase emperor whales, and bring them down with spear and harpoon. There is room below deck for comfortable sleeping and plenty of provisions and supplies. The whaling ship also provides a reason to stock a ship with rough and dangerous men, the sort who throw spears through sea monsters and drag mermaids out of the water by their hair, without resorting to trope pirates.
Other options - the adventurers-upon-return could steal any of the ships mentioned, and attempt to sail them themselves, with the addition of having ships from Lemogue pursuing them. Pirates, a King's Sloop, or any other ship could feasibly have an excuse to be at Lemogue, as it's remote location means it is one of the only places to take on provisions in the area.
The other option for reaching the Islets of Yav is the port of Olath-Nar. This is it's own adventure, as the port is a multi-racial free city that owes allegiance to no king or throne. The dark port is controlled by a cabal of dark elf outcastes. The trio of sorcerers have long since established themselves as the law of Olath-Nar, and their magical constructs keep the Sorcerer's Peace in the city. Taxes are paid, magic is limited to duels in the city Oculus Noctis Plaza, and if there is a call for a common defense, failure to muster must be compensated with a magical curse, or exile from the city. The city is home to dozens of thieve's guilds (none local to Olath-Nar, but rather safe houses for guilds from other cities), meeting houses for assassins, chantries for various not socially acceptable religions and magical traditions.
Black Ship of Olath-Nar - the very recognizable ships of the port, hewn from black wood and flying black dyed sails, are fast and deadly ships. They have a weather-mage and stormcaller as a first mate, and an elvish or half-elvish captain. As such, these ships are very expensive to hire, and most will not take on mundane adventurers-upon-return without the blessing of at least one of the Triad sorcerers. Gaining a blessing from one of these ancient magic users is going to require a good deal of luck, and likely promising most if not all of Yav's treasures to them.
Pirate Ship - plenty of pirate and smuggler ships call Olath-Nar a home port. So long as they pay a cut of their treasure to the triad, don't attack black sailed ships, and behave themselves ashore, the Triad is more than welcoming to the most cutthroat of buccaners. Hiring a pirate ship for passage is in and of itself, a separate adventure.
Cursed Ship - there are several cursed ships that rest at anchor at Olath-Nar. Passage on a cursed ship can be very cheap, or fatal, depending on the luck of the heroes, and nature of the curse on the ship. One such ship is the Suaco Elghin. The ship is manned entirely by the dead, salt cured zombies, but they retain their minds and their wits. This ship can be chartered for cheap, but anyone who loses games of chance with the crew are doomed to join the crew, while a few undead crewmen have won back their lives, to escape with whomever hired them, or to be cut down by their former mates, in a fit of jealousy and rage.
Crossing the Surging Sea
The Surging Sea is a rough body of water. Storms are common, and these whip the sea into a vicious chop. Larger ships can handle this, but smaller ships can be sunk. A ship caught crosswise by a wave can be capsized. Another concern is breaking too deeply into a wave and taking on too much water. This is a sudden way to go down and takes most of the crew and passengers down with the ahip. The waters of the Surging Sea are also cold. In the winter months there are chunks of ice floating across the sea. In a storm, these could smash a boat to splinters or leave a larger ship with a mortal wound.