Where marine licensing applies

The Marine Management Organisation (MMO) is responsible for marine licensing in:

• English inshore and offshore waters
• Northern Ireland offshore waters

In certain circumstances, the MMO is responsible for marine licensing for activities in areas beyond national jurisdiction (ABNJ)​

The MMO is also responsible for certain activities carried out by British vessels, aircraft or structures anywhere in the world.

Marine licensing can apply in tidal rivers, estuaries, near the coast, or out at sea. This guidance explains what we mean by ‘the sea’ and how tidal limits are defined.

You can check if you need a marine licence before you apply.  

Areas beyond national jurisdiction (ABNJ)

Areas beyond national jurisdiction (ABNJ), commonly referred to as the high seas and international seabed, are ocean spaces that fall outside the national jurisdiction of any single country. The Biodiversity Beyond National Jurisdiction (BBNJ) Agreement aims to ensure the conservation and sustainable use of marine biological diversity in ABNJ. Marine licence requirements for activities in areas beyond national jurisdiction (ABNJ)

English waters

English waters include:

• inshore waters – the sea within 12 nautical miles of the English coastline (the territorial limit)
• offshore waters – the sea beyond the territorial limit but within the English Exclusive Economic Zone (EEZ) and the UK sector of the continental shelf, up to 200 nautical miles from the coast

English waters do not include waters belonging to Northern Ireland, Scotland or Wales.

Northern Ireland offshore waters

Northern Ireland offshore waters are the sea beyond 12 nautical miles from the Northern Ireland coastline.

This area is designated as the Northern Ireland Exclusive Economic Zone (EEZ) and forms part of the UK sector of the continental shelf.

These waters do not include waters belonging to Scotland, Wales or England.

What we mean by the sea

For marine licensing, ‘the sea’ means any area submerged at Mean High Water Springs (MHWS). It also includes:

• estuaries, rivers and channels where the tide flows at MHWS up to the Normal Tidal Limit
• enclosed waters, such as docks, where seawater can flow in or out, either permanently or occasionally, for example through a lock

In or over the sea, on or under the seabed

Marine licensing defines locations as:

• in the sea – any location within a relevant body of water
• over the sea – directly above or overhanging the sea, such as a bridge or cantilever
• on the seabed – the ground under the sea, including anything resting on it, such as a shipwreck
• under the seabed – below the surface of the seabed, such as pipelines or cables that are buried

Tidal limits

Mean High Water Springs (MHWS)

Spring tides are when the tidal range is at its highest. Mean High Water Springs is the average of 2 successive high waters during spring tides in each month.

If you do not have specialist equipment, you should treat an area as being below MHWS if:

• it is made wet by the normal ebb and flow of the tide
• there is evidence such as markings or growth that show the tide has reached that point in the past

If you’re unsure, you should get an independent survey to confirm the position.

Normal Tidal Limit

The Normal Tidal Limit is the point in a river, estuary or channel up to which the tide normally flows. This may include areas controlled by locks.