The Annacloy River is part of a longer waterway system in County Down, Northern Ireland. It originates as the Ballynahinch River before becoming the Annacloy River, and eventually transitions into the River Quoile, which flows through Downpatrick to the Barrage and into Strangford Lough.

The upper section of the Annacloy River, from Mason's Bridge to Kilmore, offers white water paddling. From Kilmore downstream to Annacloy, the character shifts to mostly flat water with a few weirs. Paddlers should be aware of these weirs when planning this stretch. There is no official access point at Annacloy itself, though access can be gained from the bridge there.

The river downstream from Kilmore is managed by the Department of Agriculture, Environment and Rural Affairs (DAERA) for fishing, with the department leasing fishing rights on the stretch from Downpatrick to Kilmore. The south bank of this section is relatively accessible, with the road running close to the water. Paddlers should be aware that DAERA's regulations for this stretch note that boats are not allowed on the managed fishing section, so paddlers should confirm access permissions before launching in that area.

The surrounding landscape along the Annacloy and its continuation as the Quoile includes woodland and arable land. The river supports large populations of waterfowl and swans, particularly notable in winter. The stretch near Inch Abbey is considered particularly attractive, with the ruins visible from the water and the river flanked by woodland. Further downstream, the Killyleagh–Downpatrick road bridge marks the entrance to the Quoile Nature Reserve, where by-laws currently prohibit boat traffic.

For those paddling the full system as part of an organised trip, Paddle Northern Ireland runs day paddles on this river, typically running from 10:00am to around 3:00pm. Equipment hire including boat, paddles, and PFD is available through the organisation. Paddles are described as suitable for all abilities. Under-16s must be accompanied by an adult, and all paddles are subject to weather conditions. Non-members pay £10 to participate, with equipment hire available for an additional £15.