Lock Co. Roscommon

Clarendon Lock

The only lock on the Boyle River: a keeper-operated lock beside the weir at Knockvicar that lifts boats from the river onto Lough Key.

Next opening Sat, 31 Oct at 09:30
Smart Card lock

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Lock times

Next opening Sat, 31 Oct at 09:30 Worked by a lock-keeper

The next seven days
Today – Sat, 31 Oct	09:30–13:00, 14:00–18:30
Sun, 1 Nov	09:00–11:00
Mon, 2 Nov – Thu, 5 Nov	09:00–12:00

Notice: Worked by the lock-keeper in lock hours, not 13:00–14:00: +353 71 966 7011. 2 Smart Card units or €1.50 a passage, paid to the keeper. Lifejackets must be worn at the lock (Marine Notice 35/2026).

Times are worked out on this device and change with the season: check the notice. Check the Waterways Ireland marine notices

Source of the times · Times checked 23 Oct 2026

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In an emergency 112 999

Call 112 or 999 and ask for the Coast Guard. Both numbers work in Ireland and in Northern Ireland.

About Clarendon Lock

Clarendon Lock lies about 300 m above Knockvicar Bridge, beside the weir at the outflow of Lough Key. It is the only lock between the Shannon and Boyle, so every boat bound for the lake passes through it. A lock-keeper works it during the published Shannon hours, with a lunch break from 13:00 to 14:00; each passage is charged at €1.50 or two units on the Smart Card, and the keeper’s number is +353 71 966 7011. The upstream gates were replaced during a closure that ran from November 2022 into March 2023, and a 20 m floating boom now keeps boats from being drawn onto the weir: keep to the lock side. Since April 2026 everyone handling ropes in the chamber or on the lock walls must wear a lifejacket or buoyancy aid.

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