Canaston Bridge is the location in Pembrokeshire, southwest Wales where the A40 trunk road crosses the Eastern Cleddau.

It is about half a mile upstream of Blackpool Mill, at the normal tidal limit of the river.

Placed as it is on the principal line of communication from Gloucester and South Wales to Haverfordwest and St Davids, and at the point where the Cleddau ceases to be tidal, there must have been a bridge immediately upon or closely adjacent to the present site from the 12th century when transit of men and military stores to Ireland became a matter of importance.

[10] Canaston Wood is a remnant of the mediaeval Narberth Forest, which was recorded in the early 12th century.

They discovered flint scattering (mesolithic or neolithic) and evidence of early metal working.