Activities that need a marine licence
You may need a marine licence if you plan to carry out certain activities in the Welsh marine licensable area.
The need for a marine licence is set out in section 66 of the Marine and Coastal Access Act 2009.
Activities that usually need a licence
You may need a marine licence if your activity is in a licensable area and involves:
- depositing or removing materials or substances using a vehicle or vessel
- constructing, altering, improving or removing a structure in the marine area (including works over the sea, such as a bridge, or under the sea bed)
- scuttling vessels
- dredging or removing sediment
- using explosives
- incinerating objects or substances at sea
This is for permanent and temporary works.
Activities that may not need a marine licence
Some activities that would normally need a marine licence do not need one if they meet certain requirements.
Find out more about activities exempt from marine licensing.
Marine licence bands
If your activity needs a marine licence, you will need to apply for a band 1, 2 or 3 licence.
Check which marine licence you need.
The Welsh marine licensable area
The licensable area generally extends from Mean High Water Springs (MHWS) out to sea, to the edge of the Welsh zone.
This includes:
- tidal rivers and estuaries
- channels where the tide flows or could flow
- enclosed waters connected to the sea where seawater flows or could flow, such as a dock
The full legal definition is in section 42 of the Marine and Coastal Access Act 2009.
Mean High Water Springs (MHWS)
MHWS is the average height reached by the sea at high tide during spring tides.
We do not fix or publish a definitive MHWS line.
Ordnance Survey maps can be used as a guide, but they are not definitive because the MHWS line can change.
You can establish MHWS by:
- using tidal height data from the nearest port
- comparing tidal height data with a site survey at your project location
MHWS data for primary ports, including conversion to Above Ordnance Datum (AOD), is available from the National tidal predictions for UK and Irish Ports website.
More local data may also be available to buy.
If you are not sure whether you need a marine licence
Get advice before you apply or contact the marine licensing team for advice.