The Hawaiian language (ʻŌlelo Hawaiʻi) has no traditional word for "roller coaster"—a modern amusement park invention. There is no direct, idiomatic translation.
A creative, descriptive approximation sometimes offered is:
"Kaumahauna lupe haele wawae" – literally "rolling waves ride" or "wave-traveling feet ride."
This is a modern coinage, not a traditional term. For contemporary contexts (e.g., theme parks in Hawaiʻi), English "roller coaster" is commonly used, or the descriptive phrase "kaʻa holo pēpē" ("baby car ride") might be adapted playfully.
Note: Hawaiian orthography uses ʻokina (glottal stop) and kahakō (macron for long vowels). Proper spelling matters for meaning.