What does this verse from Mike Oldfield's Foreign Affair song mean?
a lagoon by la mere
Taking a look at the verse as a whole....
Foreign affair.
Take a trip in the air
To a tropical beach,
An island to reach.
A new territory
For an intimate story,
A lagoon by la mere.
It's a foreign affair.
... I would imagine that 'la mere' is an anglicization of the french 'la mer', which quite literally means 'the sea'.
A lagoon is a shallow body of water separated from a larger body of water, quite often from the sea, therefore 'a lagoon by la mere' is a shallow lake, cut off from the ocean, which is quite in keeping with the tropical island setting of the song.