1,920-acre reservoir on the North Island of New Zealand, located in the Waikato Region approximately 19 miles southeast of Hamilton. Formed by the Karapiro Dam on the Waikato River — completed in 1947 — the lake has an L-shaped profile and is internationally recognized as a world-class flat-water venue, having hosted the 1978 World Rowing Championships and the 1950 British Empire Games. The lake is owned by Mighty River Power and serves as home to the New Zealand National Rowing teams. Paddlers should be aware that rowing, waka ama, powerboating, water skiing, and wakeboarding all take place on the lake, meaning vessel traffic can be significant.

Multiple access points are distributed along the lake's length. Near the dam, Karapiro Domain provides a boat ramp giving access to the western arm. Further along State Highway 1, Keely's Reserve and Monaroa Reserve both have boat ramps accessing the mid-reaches. Bob's Landing on the Karapiro Straight offers additional entry, located below the Tirau Road and Maungatautari Road intersection. Horahora Domain off Maungatautari Road has ramps leading to "Stumpy Bay" and the southern reaches of the lake, with camping available for fully self-contained campervans. Little Waipa Domain on Horahora Road, where the Waipa Stream enters the lake, provides access to calm backwaters and swifter upstream sections, and also permits self-contained campervan camping. Finlay Park and Epworth Camp on the western side near Horahora have boat ramps but require prior arrangement as they are privately managed. Aniwanawa Reserve near the Pokaiwhenua Stream mouth is foot-access only.

The lake features a mix of open water and narrower inlets, with calm backwaters particularly around the tributary mouths of the Pokaiwhenua and Little Waipa streams. The area upstream of the dam spillway involves fast and unpredictable currents and is described as difficult to navigate by boat. Paddlers should note that lake levels can fluctuate noticeably due to hydroelectric operations, which can affect conditions in shallower areas.

Biosecurity regulations require paddlers to Check, Clean, and Dry all gear before entering the lake, as the area falls within an invasive freshwater clam management zone. Guided kayak tours, including glow-worm evening tours and waterfall inlet trips, are operated by several local companies, and kayak and stand-up paddleboard rentals are available nearby.