Captain is a senior officer rank of the Royal Navy. It ranks above Commander and below Commodore and has a NATO ranking code of OF-5. The rank is equivalent to a Colonel in the British Army or Royal Marines and to a Group Captain in the Royal Air Force.
In the Royal Navy, the officer in command of any ship is considered the captain even if that officer holds a different rank. Royal Navy officers who rank as captains may serve on ships or on land in naval bases or other service establishments.