East coast Northumberland Flood
Alnmouth to Dunstanburgh Castle: a shelter-to-castle day on the Northumberland coast
This is the classic Northumberland starter paddle: a shallow estuary launch, two miles of dune-backed sand, then a whin sill headland with a castle sitting on top of it. At 8.5 nm return it fills a comfortable half day, and the whole run sits inside a bay that knocks down anything under a force 4 westerly.
- Distance
- 8.5 nm
- Tide window
- 2.4-3.9 m springs, 1.2-2.0 m neaps
- Wind limit
- 12 kt
- Grade
- Sheltered
- Published
- 2 Aug 2026
Why the bar dictates the whole day
Alnmouth Bay is shallow and open to the east, and the Aln estuary mouth has a shifting bar that moves west after every big northerly. On a 3.9 m spring the bar carries well over a metre of water at high water; on a 1.2 m neap at half ebb it can be dry sand with a two-knot stream running through a channel you cannot see from the beach.
The practical rule is to launch at high water slack, paddle north on the first of the ebb and be back on the slipway no later than two hours after high water. That gives you roughly five hours of water and keeps you off the bar on the return.
The paddle north to the castle
Leave the estuary mouth and turn north along the dunes. For the first 1.5 nm you are in 2-4 m of water over sand, with the bottom clearly visible and a light surf line on your left. The dune field here is a Site of Special Scientific Interest, so keep 50 m off the sand and do not land between the flagged access points.
At the two-mile point the character changes completely: the whin sill reaches the sea as a low dark sill of rock, and Dunstanburgh Castle appears above it. In any swell over 1 m the base of the sill produces clapotis, bouncing reflected waves that arrive from two directions at once. Paddle 200 m offshore here and the water flattens almost immediately.
Landing at the castle
The only sensible landing is the small beach at Craster, 0.6 nm past the castle, where there is a stone harbour wall that shelters the inner corner in anything up to a force 4 southeasterly. Do not attempt to land directly below the castle: the beach there is steep shingle with a shore break and no shelter from the northeast.
Craster has a public toilet, a cafe and a fresh water tap at the harbour wall. If you are running a group, this is the natural turn point and lunch stop before the return.
Return and the tide gate
The return is the same water in reverse, but the light on the dunes is now behind you and depth judgement gets harder. Keep to the outer edge of the bay on the way back rather than cutting close to the dunes, because the ebb drains the inner bay first and you can find yourself on a drying bank a mile from the slipway.
If the wind has built to a force 4 from the east while you were ashore, take the inner line: aim for the spire of Alnmouth village and follow the channel markers on the estuary wall. The ebb runs at up to two knots across the mouth on springs, so ferry across it rather than fighting it head on.
Plan table
Before departure
- 01
Check the Alnmouth tide table, not the Amble one
Local high water runs 12-18 minutes before the standard port figure. Two hours either side is your window.
- 02
Confirm the bar by eye from the estuary footbridge
A continuous white line right across the mouth means no passage until the next flood.
- 03
Log a shore contact and a return time
Mobile coverage is good in Alnmouth and Craster but drops at the castle base under the sill.
- 04
Pack for cold water, not for air temperature
North Sea here sits between 7 C in March and 15 C in August. A 3 mm suit and a windproof top is the working minimum.
En route
- 01
Hold 200 m off the sill between Dunstanburgh and Craster
This is the single line that removes the clapotis from the day.
- 02
Watch for pot buoys off Boulmer
A string of small lobster pots runs 400 m offshore between Boulmer and Howick.
- 03
Keep a listening watch on channel 16 around Craster
The Craster-to-Boulmer inshore ground is used by small potting boats working out of Amble.
- 04
Start the return no later than two hours after high water
Miss that gate and the bar becomes the deciding factor instead of you.
Key numbers
- 8.5 nm return, 3-4 hours of paddling plus a lunch stop at Craster.
- Launch window: two hours either side of Alnmouth high water.
- Wind limit 12 kt; anything above that from the east makes the castle base unworkable.
- Land at Craster, never directly beneath the castle.
- Best months: May to early October for settled weather; the coast is paddleable year-round with a dry suit.
Bail-outs
- B1 Boulmer beach, 3.5 nm north, landing through a shingle bank
- B2 Warkworth Harbour inside the Coquet mouth, all states of tide
Return leg：Run back south on the first of the ebb with the castle on your starboard beam; the ebb sets you gently onto the Aln bar rather than across it.