Scottish Greens minister Lorna Slater has been accused of hypocrisy for using a private ferry for an official visit to an island.
The boat was hired to take a group of eight people, including Ms Slater, to Rum.
The Scottish Government said it would ensure the best value for taxpayers and allow Ms Slater to "maximise time on the island".
But the Conservatives questioned why Ms Slater did not take a CalMac ferry.
And they predicted that the government's decision to hire a private boat would anger islanders struggling to access lifeline ferry services.
The circular economy minister was travelling with members of the Isle of Rum Community Trust, as well as NatureScot and Scottish Government staff on a charter operated by Western Isle Cruises.
Spend more time
The minister's spokesperson said this would allow her to spend more time on the island and support a small local business.
The Scottish Conservatives described it as a "vessel of hypocrisy", saying that islanders have been concerned about the current provision of timetabled ferry services.
The BBC says the ferry network faces continuing problems with reliability due to an ageing fleet, something which has long angered island communities.
Donald Cameron, a Tory MSP for the Highlands and Islands, said the Greens were "forever lecturing the public on the need to use public transport", but Ms Slater was "happy for the Scottish Government to charter a private boat to take her to and from Rum".
He added: "Her excuse for doing so - that, essentially, the CalMac timetable doesn't suit - will go down like a lead balloon with Scotland's island communities.
"Those who rely on lifeline ferry services don't have the luxury of hiring a private boat to travel.
'Scandalous incompetence'
"Instead, they are dependent on an ageing and unreliable CalMac fleet they've been lumbered with due to the scandalous incompetence of the government Lorna Slater is at the centre of."
He accused Ms Slater of "breath-taking" hypocrisy and lack of self-awareness, and added that the "tone-deaf indifference to them" was "another kick in the teeth to betrayed islanders".
A Scottish Labour spokesperson said: "This is stunning hypocrisy. While island communities are facing serious disruption to ferry services, Lorna Slater is chartering a private boat.
"The Greens are out of touch with working people and nothing more than the SNP's little helpers. Scotland deserves better."
- Around 60 people were left stranded overnight on Arran on Saturday after the last ferry was cancelled by thick fog.
Many passengers, including a children's football team, said they had to pay for alternative accommodation on the island on Scotland's west coast.
Some were refused boarding to the 6.30pm service when the 7.20pm sailing was cancelled at just two hours notice.
Operator CalMac said the MV Alfred ferry had reached capacity quickly.
The catamaran, which can carry 430 passengers and 98 cars, only began operating on the Firth of Clyde route on Friday.
The BBC says it was brought into service between Arran and Ardrossan to support the main ferry, MV Caledonian Isles, which can carry up to 1,000 passengers.