HMS Dumbarton Castle (P265) was an offshore patrol vessel of the British Royal Navy. Her main role was the protection of the offshore assets of the United Kingdom, including oil and gas installations and fisheries out to the 200 mile (370 km) limit.
She spent much of her time deployed in the South Atlantic as guard ship, patrolling around the Falkland Islands and South Georgia, alternating with her sister HMS Leeds Castle. Her long association with the Falkland Islands resulted in the ship's company being given permission to add her name to the roll of honour written in white rocks on the hillside opposite Stanley in 2007.
Dumbarton Castle was replaced by a River class-based vessel, HMS Clyde, in early 2008.
Both Dumbarton Castle and her sister were sold to Bangladesh in April 2010. Dumbarton Castle left Portsmouth on 21 May 2010 towed by the tug Multratug 7, for A&P Group facility in Newcastle upon Tyne for a major regeneration project with her sister ship HMS Leeds Castle. The project was completed in December 2010.
In March 2011, the Leeds Castle and Dumbarton Castle was recommissioned as the Dhaleshwari and Bijoy of the Bangladesh Navy respectively.