Angus MacNeil, who represents Na h-Eileanan an Iar, said links under the Sound of Barra, Sound of Kerrera off Oban and between Mull and the mainland would allow five ageing ferries to be retired.
He added that a tunnel between the Isle of Harris and Skye was also “not out of the question.”
The MP pointed to the example of the Faroe Islands where a network of 17 land tunnels and two subsea tunnels has been built.
Mr MacNeil has now written to transport secretary Michael Matheson suggesting the Scottish Government visit the Faroes to learn from its experience, the Herald reported.
“The transport network in the Faroes is the kind of system we should aspire to follow in the Scottish islands,” he said.
“The Sound of Barra, Sound of Kerrera and a link from Mull are all prime examples of what could be done and a tunnel from Harris to Skye is also not out of the question.
“Infrastructure of this kind would have huge economic and social benefits to all parts of the islands and would remove travel disruption due to weather conditions or issues associated with capacity.”