Rental car prices in Hawaii can vary considerably between different rental car agencies as the competition is pretty fierce. Oahu is the only major Hawaiian Island where visitors stay without renting a car. Waikiki is small and walkable and many activity companies will shuttle you to their locations. If you are trying to save money and spend much of your trip in Waikiki, get a rental car for at least some part of the trip to explore sights that the city buses and even the tour buses do not visit.
When renting a car, unless you booked an accommodation that includes parking, and we have a few of those, you will need to pay parking fees which can add a considerable cost to renting a car. Our recommendation is to consider renting a car from within Waikiki, perhaps for a day, and then you do not have to pay the exorbitant parking rates. If you are lucky, you might score the free street parking but the street parking is very limited and may not be conveniently located near your accommodation.
If you want a fun alternative transportation, many places in Waikiki rent mopeds or scooters that are convenient to zip around Waikiki and the nearby areas.
Oahu has some of the most confusing roads and highways in the United States. Roads change names randomly and there is no logic to the layout of the roadways. You cannot drive around the circumference of the island as once you get to Keana Point the road ends. The three interstates, which do not connect to another state, are simply named H1, H2, and H3. A mistake is to assume if you exit an interstate that you can simply get back on and head in the opposite direction. Do not let the road ways drive you mad, if you use Google maps or other mapping application, you increase the likelihood that you will get to your destination. Also we claim to have the worst traffic in the United States and our rush hour traffic can be heavy but the island is only 597 square miles with 112 miles of coastline and 44 miles from east to west and 30 miles from north to south.
For directions, locals usually describe places as being on the mountain or mauka (mao-ka) side of the road or toward the ocean or Makai (ma-ki) side of the road.
It is best not to leave anything valuable in your car. Rental cars are easy to spot and are targeted by thieves. If you are going to store items in your trunk, do so at a different location then where you park the car.