Atlantis, which owns the world's largest planned tidal stream energy project MeyGen, has signed a seabed lease for 25 years with The Crown Estate.
The Crown Estate granted the lease after MeyGen satisfied the obligations for extensive development as was included within its five-year agreement for lease, which was signed in October 2010.
This 398MW 25-year lease is said to be the largest in marine energy to be awarded by The Crown Estate, and the first in the Pentland Firth and Orkney Waters region.
MeyGen CEO Dan Pearson said: "Signing the Lease with The Crown Estate is a significant achievement being the first of its kind and demonstrates how a commercial scale energy project can be designed, consented, engineered and funded within four years.
"This is the culmination of a talented and committed team working alongside stake-holders and governments who are determined to launch a new energy sector within Scotland and the UK."
The Crown Estate ocean energy head Ronnie Quinn said: "Our commitment to invest in and agree a lease for the Meygen project continues our strategy to explore tidal stream energy on a commercial scale and its potential to help unlock the nation's tidal energy resources over the long-term."
Recently, Atlantis agreed terms with a syndicate for the funding of Phase 1A of the MeyGen project and construction of the project is expected to begin in the fourth-quarter of this year, while the first power to the grid and revenues to be earned will be in the first half of fiscal 2016.