It could be more accurately described as a land-locked archipelago.
"Command"
William McFee
He is full of interesting information about both Lower and Upper Burmah, the Mergui archipelago and natural history.
"From Edinburgh to India & Burmah"
William G. Burn Murdoch
Maulmein, Ye, Tavoy, Tenasserim, and the Mergui archipelago.
"The Ethnology of the British Colonies and Dependencies"
Robert Gordon Latham