Author: Austin Goudge

The information below is an update to the local notice to mariners 06/2026 and 08/2026

All mariners are advised that The Environment Agency/Briggs Marine are scheduled to undertake a small scale scientific survey (sediment grab sampling) .

Date: 1st  June – 31st  June 2026.  
Duration: 2 Days
Activity:  Day grabs at 2 locations in Conwy Bay/Estuary and 2 locations in Red Wharf
Bay.
Vessel: CSV Severn Guardian   MMSI: 235091052   Callsign: 2FGL5   VHF: Ch. 16
Skipper (Briggs Marine): Mark Wiliams ([email protected])
Survey Officer (Environment Agency) :Richard Pritchard ([email protected])
 

Matthew Forbes
MSc LLB (hons) BSc AFNI
Conwy Harbour Master

The information below is an update to the local notice to mariners 06/2026 issued on the
12/05/2026.

All mariners are advised that The Environment Agency/Briggs Marine are scheduled to undertake a small scale scientific survey (sediment grab sampling) . The surveys are likely to be done between  12th June to 15th June.  

Duration : 1 Day
Activity:  Day grabs at 2 locations in Conwy Bay/Estuary and 2 locations in Red Wharf Bay.
Vessel: CSV Severn Guardian   MMSI: 235091052   Callsign: 2FGL5   VHF: Ch. 16
Skipper (Briggs Marine): Mark Wiliams ([email protected])
Survey Officer (Environment Agency) : Tom Lord ([email protected])

Matthew Forbes
MSc LLB (hons) BSc AFNI
Conwy Harbour Master

Open Water Swimming Event. Sunday, 31st May, 2026.

An Open Water Swimming Event will commence at 10:40am from Menai Slipway and finish at Y Felinheli – ETA 12:40pm . Swimmers will be keeping to the Anglesey side and will cross over at Plas Newydd – ETA 12:10pm .

They will be accompanied by safety kayakers and powerboats.

Please exercise caution when navigating in the vicinity of the event.

This notice replaces NtoM 31-05-26

David John O’Neill
Harbwr Feistr Caernarfon Harbour Master

Mariners are advised of the current positions of the Aids to Navigation listed below.

CAERNARFON HARBOUR TRUST FLOATING AtoN POSITIONS DEPTH IN CHANNEL

Aid to Navigation	Approximate Depth (5 metres off correct side of AtoN, adjusted to CD). WARNING: Depth will be affected by wind, atmospheric pressure and sea state.	Latitude	Longitude	Light
LLANDDWYN ISLAND SW ROCK BUOY S CARDINAL	10.1m	53ᵒ 07’.81 N	004ᵒ25’.05 W	Unlit
LLANDDWYN ISLAND NE ROCK BUOY S CARDINAL	2.67m	53ᵒ 08’.04 N	004ᵒ24’.47 W	Unlit
SAFE WATER MARK	7.58m	53ᵒ 06’.95N	004ᵒ25′.14 W	L Fl.10s
C 1 STARBOARD	5.01m	53ᵒ 07’.00 N	004ᵒ24’.69 W	Fl.G.5s
C 2 PORT	0.51m	53ᵒ 07’.19N	004ᵒ24’.32 W	Fl.R.10s
C 3 STARBOARD	1.99m	53ᵒ 07’.23 N	004ᵒ 23’.88 W	Q.G
C 4 PORT	2.43m	53ᵒ 07’.12 N	004ᵒ22’.74 W	Q.R
GRAMPIAN CASTLE S CARDINAL	1.33m	53ᵒ 07’.26 N	004ᵒ 22’.96 W	VQ(6)+LFl.10s
C 5 STARBOARD	1.46m	53ᵒ 07’.28 N	004ᵒ23’.21 W	Fl.G(2).5s
C 6 PORT	2.78m	53ᵒ 07’.16 N	004ᵒ21’.97 W	Fl.R.5s
MUSSEL BANK PERCH	3.94m	53ᵒ 07’.32 N	004ᵒ20’.92 W	Fl.R(2).5s
C 8 PORT	1.78m	53ᵒ 07’.63N	004ᵒ19’.43 W	Fl.R.3s
C 10 PORT	2.48m	53ᵒ 07’.95 N	004ᵒ18’.20 W	Q.R
C 7 STARBOARD	3.08m	53ᵒ 08’.14 N	004ᵒ17’.99 W	Q.G
C 12 PORT	2.54m	53ᵒ 08’.49 N	004ᵒ17’.37 W	Fl(2)R.10s
C 9 STARBOARD	3.38m	53ᵒ 08’.56 N	004ᵒ16’.89 W	Fl.G.2s
CHANGE BUOY S CARDINAL	3.95m	53ᵒ 08’.80 N	004ᵒ16’.74 W	VQ(6)+LFl.10s
SEIONT RIVER BIFURCATION	-1.06m	53ᵒ 08’.54 N	004ᵒ16’.82 W	Unlit
TRAETH GWYLLT STARBOARD	3.92m	53ᵒ 09’.27 N	004ᵒ16’.09 W	Fl(2)G.10s
C 13 STARBOARD	1.66m	53ᵒ 09’.53 N	004ᵒ15’.89 W	Fl(4)G.10s
C 11 STARBOARD	2.26m	53ᵒ 09’.88 N	004ᵒ15’.63 W	Fl(2)G.5s
C 14 PORT	4.81m	53ᵒ 10’.18 N	004ᵒ15’.53 W	Fl.R.5s
C TEMP PORT	4.97m	53ᵒ 10’.53 N	004ᵒ14’.67 W	FL(2)R.5s
C 9 STARBOARD PORT DINORWIC	2.76m	53ᵒ 10′.63N	004ᵒ13’.82W	FL(3)G.10s

David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Ymddiriedolaeth Harbwr Caernarfon Harbour Trust