A British couple and an Australian yachtsman ran into trouble when they sailed towards a disputed island in the Strait of Hormuz, between Iran and the United Arab Emirates.
But why is the island so sensitive that it prompted Iranian authorities to hold them under armed guard for 13 days while they questioned them repeatedly?
Abu Musa is a small island, about 12 sq km, and seemed a good destination for Rupert and Linda Wise with Australian Paul Shulton as they took their yacht on its maiden voyage from Dubai.
After checking maps and asking some locals, they decided that the harbour and marina looked just the spot.
What the maps didn't appear to tell them was that Abu Musa is heavily fortified, populated by soldiers and the cause of tension between Iran and UAE.
As two gun boats approached and 10 men surrounded them they must have wondered what they had sailed into.
Abu Musa, with neighbouring Greater and Lesser Tunbs, are strategically important in the Gulf as one-fifth of the world's oil supply passes by them.
Iran seized the Greater and Lesser Tunbs in 1971 and annexed Abu Musa in 1992 and has been in dispute with the UAE since.
The UK's Foreign Office said "relations with Iran have been soured by the dispute".
And in the "war of the tankers" during the 1980s, Iran fired missiles at Iraq's tankers from there.
"It's a boiling strategic issue because it's key for tanker traffic," said Middle East editor for Jane's Country Risk David Hartwell.
"The Iranians are very, very sensitive about anything that comes close to the island."
The UAE has no presence on the island but sees custody of it as a sovereign issue.
It has offered to allow the International Court at the Hague to settle the dispute.
Iran, however, has made it clear it does not welcome intervention by any outside body.
That presumably applies to errant sailors.
Mr Hartwell said: "Given that they were British, that they were sailing towards a sensitive island, given the pressure that Iran is under at the moment, regarding the nuclear issue and Iraq - then they are going to react pretty adversely."
The trio were released without any charge or even knowing why they had been apprehended.
Initial questioning by the officials focused on spying and the possibility that it was "a subtle probe" into ownership of the island, but they soon gave up on that tack, Mr Wise said.
But with the navy, judiciary, ministry of information and ministry of foreign affairs all involved, the Iranians were clearly being cautious about the unwelcome visitors.