Nightgaunts snatch them, carry them high into the freezing and barely-breathable air on the very verge of the North Wind, and dump them someplace horrible.

Ixian necromancer-slavers land and take them captive.

Rel is passing through and challenges them to a game of dice.  If they win, he sends them somewhere almost reasonable.  But if they lose...

They descend into a volcano, travel through an underground hellscape, and are eventually ejected elsewhere in Hyperborea by a giant geyser or whirlpool.

The snake-men have a partially-disassembled Atlantean airship hidden in a cave.  It can be put in working order if the missing parts are retrieved from the hideous monsters that guard them.

They lasso a monster sea serpent, sacred to Yig, and ride it to safety (sea serpents won't submerge if they have riders... probably).

A mysterious ice berg floats past, and they are able to hitch a ride.  Needless to say, it is riddled with tunnels and crawling with ice daemon servitors of the Ashen Worm.

A powerful magician arrives on the island and offers to teleport them in exchange for some terrible bargain.

Last but not least: swim for it!

Great stuff! Sometimes it's OK to also allow the campaign to sweep over several months. We had a similar situation recently where the party was dropped off and the captain got tired of waiting. They were stranded on the island, which was only about 75 miles away from the next center of population, so they went about the task of taking an old, ruined sailboat and restoring it for the journey across the strait. It took months. Times like these I like to talk to them about magician and clerics developing their next spells (the "automatics" from level gains) and also discuss other classes developing skills that they will have in the future (future level gains). I find it valuable to slow things down, and broaden the lens, as it were. Before you know it, we'll be back to about three sessions of game play all taking place during one day in the actual campaign.