Fierce
Mākaha means fierce or savage. The valley was known for bandits who waylaid travellers on the coastal trail, and the name records it.
The word also names the sluice gate of a fishpond — the grating that let small fish in and kept big ones out. Both senses are current; the valley takes the first.
The wave
Mākaha's winter surf break was the site of the first major surfing competitions in Hawaiʻi from the 1950s, and it remains one of the most serious big-wave spots on the island.