Lulumahu Falls was a once-forbidden 70ft waterfall sourced from the headwaters of Nuuanu Stream (near the Pali Lookout), where getting there wasn’t obvious.
Waimano Falls seemed like more of a locals waterfall near Pearl City with a 30-40ft drop followed by a cascade with a deep plunge pool and a rope swing.
Laie Falls (or La’ie Falls) is a light-flowing 15ft waterfall reached on a lengthy 6-mile round-trip hike in the Ko’olau Mountains above the town of La’ie.
The Jackass Ginger Pool is really more of a swimming hole than a waterfall attraction found by following the stream after deviating from the Judd Trail.
Likeke Falls is a pretty 30ft waterfall that was apparently the result of a broken ditch further upstream. So I guess you can say this waterfall isn’t natural.
Waimea Falls is a popular 45-55ft waterfall and swimming hole with a lifeguard reached by a stroll through a botanical garden in the North Shore of Oahu.
Sacred Falls is hands down the most beautiful waterfall on O’ahu where the bottom of this 1100ft waterfall was once accessible along a trail in a narrow canyon.
Manoa Falls is a very popular waterfall reached on an hour-long hike through a jungle sprinkled with bamboo near the University of Hawaii inland from Waikiki.
Maunawili Falls is a small but popular 15-30ft waterfall and swim hole reached after a jungle hike with a few stream crossings that began in a residential area.
Kapena Falls is a tiny waterfall tumbling around 20-30ft accessed either from a cemetery (with Alapena Falls en route) or from a Pali Highway pullout scramble.
Waikahalulu Falls is an urban park waterfall maybe 10ft tall nestled in the somewhat hidden Lili’uokalani Garden set in the busy maze-like streets of Honolulu.