Looking over the Cromarty Firth which has in the past had 17 rigs stacked.

These rigs need periodic surveys and they come in and get work done – major maintenance or to install client-specific equipment top-side – before going back out to drill.

There are six ‘hot-stacked’ which are on ‘warm standby’, ready to go with 60 onboard, and another six ‘cold-stacked’, empty.

According to the BBC in August 2017 two men boarded a cold stacked rig:

'The pair, who describe themselves as "urban explorers", took a dinghy to the Ocean Princess, one of several offshore structures in the Cromarty Firth.

Police Scotland said it was aware of the incident and has begun an investigation.

The platform's owner, Diamond Offshore, confirmed an incident took place.

The Cromarty Firth Port Authority has declined to comment.

The incident is understood to have happened at the weekend and the men were thought to have spent a night onboard.'