Police are still searching for two Greenpeace volunteers who vanished after abandoning their occupation of an oil rig.
The protesters had tied themselves to Enterprise Oil's Jack Bates platform in the Cromarty Firth on Sunday and spent the night there before coming down at 1600 BST on Monday. Grampian Police then lost sight of them.
The protesters left the rig after being ordered to come down by a judge in Edinburgh who granted Enterprise Oil an interdict.
The semi-submersible rig, which has been under charter to Enterprise Oil and had undergone a refit, was preparing to leave its anchorage to begin drilling off the Outer Hebrides when a group of protesters climbed on board.
Two protesters stayed on the rig through the night while another five people, allegedly involved in the action, were charged with breach of the peace.
Greenpeace spokesman and climate and energy campaigner Rob Gueterbock said: "We decided the climbers should come down because our fight is not with the courts. But it is a sad day for the sensitive environment of the Atlantic Frontier and a sad day for our environment. All the main environmental bodies in Scotland, England and Wales have backed us in opposing the drilling for oil west of Shetland."
