Albert Barnes on Acts 27:4

We sailed under Cyprus. For an account of Cyprus, Acts 4:36. By sailing "under Cyprus" is meant that they sailed along its coasts; they kept near to it; they thus endeavoured to break off the violent winds. Instead of steering a direct course in the open sea, which would have exposed them to violent opposing winds, they kept near this large island, so that it was between them and the westerly winds. The force of the wind was thus broken, and the voyage rendered less difficult and dangerous. They went between Cyprus and Asia Minor, leaving Cyprus to the left. Had it not been for the strong western winds they would have left it on the right.

The winds were contrary. Were from the west, or south-west, which thus prevented their pursuing a direct course. See the Map.