The Brecon & Abergavenny Canal runs from a terminus at Brecon to Pontymoile Junction where it joins the Monmouthshire Canal, which then ran to Newport with an arm to Crumlin joining at Malpas Junction. The Brecon & Abergavenny Canal, which is 33.3 miles (53.6 km) long and has 6 locks is fully navigable. The Monmouthshire Canal is mostly under restoration, with only the 2.2 miles (3.5 km) from Pontymoile Junction to Cwmbran Tunnel fully navigable. The Canals are isolated from the main connected network of waterways in England and Wales.
The maximum size of boat that can use the Brecon & Abergavenny Canal is
length: 60' 0" (18.29 metres) - Llangynidr Locks
width: 9' 2" (2.8 metres) - Llangynidr Locks
headroom: 5' 6" (1.67 metres) - Ashford Tunnel
draught: 4' 7" (1.4 metres) - cill of Langynidr Locks - but silting means the canal is much shallower than this in many places.