Swartvlei is the largest and deepest lake in the Garden Route National Park, situated near Sedgefield in the Western Cape. The lake covers approximately 9 square kilometres and reaches depths of up to 16 metres. It forms part of a complex estuarine system connected to the Indian Ocean, with the mouth open to the sea for roughly six months of the year. When the mouth is open, tidal influence on the main lake body is limited by a bottleneck at the railway bridge.

Canoes, kayaks, and other watercraft are permitted on Swartvlei, but all require permits, which are available from the SANParks office at Ebb and Flow. Paddlers must also adhere to no-wake zones. SANParks has placed cardinal markers on the vlei to indicate the main sandbanks; some peripheral sandbanks become very shallow when the river mouth is open, though they are generally visible.

There are two main access points. Pine Lake Marina (PLM) on the northwest side of the lake offers paid access at R90 per day or R600 per year, with ablution facilities including toilets and showers available between 08h00 and 17h00, a restaurant and convenience shop approximately 300 metres from the boathouse, and a rescue boat and team on the water between 08h00 and 17h00. A second launch point is located at the bottom of Kingfisher Drive, where parking and ablution blocks are available, though parking can be tight during high season. A third access point at Bleshoender off the N2 is technically free but described as very difficult, requiring a 4x4 vehicle; the area is heavily overgrown and waterlogged, with reeds that may damage equipment.

The estuary section between the river mouth, around the island, and up to the N2 road bridge is specifically noted as a worthwhile paddle. Guided kayak tours of the Swartvlei wetland area are also available through local operators.

Birdwatching is a notable feature of paddling here, with waterfowl, kingfishers, and fish eagles regularly sighted. The lake is managed by SANParks as part of the Garden Route National Park, and conservation regulations apply throughout.