Haha, I guess you stayed in a holiday rental house on the water, probably in Witta Circle?
It does happen all the time, people who are on holidays are pretty careless, often lock the front door ect. but leave the back unlocked/completely open often with things sitting out on the back veranda.
Someone drives up in a boat, hops out, grabs a load of your stuff and drives back off.
I deliver rental kayaks to the places all the time and tell people to be careful, but every now and then someone still gets their stuff nicked even after being warned. The holiday rental companys should really give you some sort of warning.