Honolulu International Airport (now officially Daniel K. Inouye International Airport) is the main gateway to Hawaii, with direct flights from mainland US cities (Los Angeles, San Francisco, Seattle, New York), Australia, Japan, South Korea, and several other Pacific destinations. From the US mainland the flight is about five hours from the West Coast and ten hours from the East Coast. Hawaii is not connected to the mainland by road or sea for independent travellers.
From the airport to Waikiki, the cheapest option is TheBus (route 20, about 90 minutes). Shared shuttles take about 45 minutes. Taxis and rideshares are faster but expensive. Renting a car at the airport is the best option if you plan to explore the island beyond Waikiki.