In 2026, Hawaii is overwhelmingly a "Digital Payment" economy, and you can use a credit card or mobile wallet (Apple/Google Pay) for 99% of your expenses, from high-end resorts to local ABC stores. However, carrying a small amount of cash ($50–$100 in small bills) is a peer-recommended "high-value" essential for three specific reasons: Tipping, Farmers Markets, and Food Trucks. If you are heading to a local "Plate Lunch" spot in Hilo or a roadside fruit stand on the Road to Hana, they may have a "Cash Only" policy or a $10 minimum for cards. Additionally, tipping your valet, bellhop, or "Manta Ray" dive guide is much easier and more appreciated in physical cash. A peer-to-peer "win" for 2026: while you don't need a "thick wallet," having a few $5 bills ensures you can support the local "mom-and-pop" businesses and provide immediate gratitude for high-value service during your island adventure.