The following are a few suggestions of some things to do and see on Oahu. Probably we are biased because we live here, but so be it. We organize them by distance from Waikiki. An island map, available at the bookstore or any convenience store will prove helpful.
Locals use a circular coordinate system. Forget North-South-East-West, here in Hawaii directional references are the mountains (mauka) and the ocean (makai) and major landmarks indicating clockwise or counterclockwise around the island (eg., Koko Head or Ewa).
One inexpensive way to get around Oahu is by the bus (current fare is $2 for adults, exact change required, transfers free), which is called ``The Bus". Call 848-5555 for the bus times and routes information, or check here http://www.thebus.org/route/routes.asp
Operated by the University, it is small compared to some others, but nice and obviously specializes in local fishes. It is at the beach, just West (Ewa) of the Kaimana Beach Hotel. (2777 Kalakaua, phone 923-1771, from 9 a.m. to 5 p.m. daily, general admission for adults $9, students and seniors $6). http://www.waquarium.org/
You must go around to the North-East (mauka-koko head) side and drive into the center of the crater through a tunnel. (Do not think of climbing up the outside: the rock is rotten and very dangerous.) Park in the obvious place and hike up a well marked trail in about 45 minutes. It can be hot in the sun, particularly since the trail includes 99 concrete and steel steps. You may want to take a flashlight for the section which goes trough a tunnel. The view is great. They close the park fairly early. http://gohawaii.about.com/cs/oahuactivities/a/diamond_head.htm
There are many buildings left from the Monarchy and Colonial times (eg. missionary houses, Iolani Palace). Can't say much, as we have never done the tour, but various relatives enjoyed it. Consult a guide book or http://www.aloha-hawaii.com/oahu/honolulu/
Walking around the Chinatown area is certainly fun. The Oahu market area (corner of King and Kekaulike) is particularly delightful on a Saturday morning. You will hardly believe you are in the USA. Several blocks mauka (inland in the local coordinate system) you will find the Chinese Cultural Plaza, which has many interesting restaurants and shops. This area also has much Philipino and Vietnamese influence. http://www.chinatownhi.com/
There are several easy hiking trails on Tanatalus and adjacent ridges just a mile or two from the university (here and here). Even if you do not go on the hike you may still want to take this lovely loop drive up nearly 2000 feet. It has spectacular views of the city, especially from Puu Ualakaa Park, and gives a nice feel for the lush mountain landscape. You will need a street map of Honolulu. It is a good place to go see the sunset, much favored by local romantics. Takes about one hour round trip, plus stops, from Waikiki. (map here).
Located on Beretania at Ward, it is a lovely small museum with nice colonial style architecture, and often excellent visiting exhibits. It also has a nice gift shop. http://shop.honoluluacademy.org/
The oldest botanical garden in Hawaii, a compact arboretum of exotic species, is a wonderful place for a picnic lunch. There are some huge baobab and kapok trees, the garden has an interesting ``prehistoric garden", and a magnificent orchid collection. http://www1.honolulu.gov/parks/hbg/fbg.htm
The natural history museum. Has comprehensive exhibits on Hawaiian and Polynesian natural and cultural history. Also has a good museum shop. http://www.bishopmuseum.org/
The premier snorkeling spot, an underwater reserve in an old broken out volcanic crater. Mask and swim fins gets you access to an underwater fantasy. Be sure to go early in the morning (9 a.m.) to beat the tour buses there. It is closed sometimes now to give the beasts a chance to recuperate, probably Wednesday mornings, but you might check before going there. They do restrict entry when the park is full! And they have started to charge a $7.50 entrance fee, plus $1 for parking. http://www1.honolulu.gov/parks/facility/hanaumabay/
High spot on Pali highway with spectacular view off steep cliffs of windward (Northeast) Oahu. Don't go there at late hours, and do watch out for the high winds. (Also don't carry pork products… ask a local to explain). http://en.wikipedia.org/wiki/Nu%E2%80%98uanu_Pali
Hawaii's version of Marineland. Good place. Drive around the Koko Head (east) end of the Island to Makapuu, about 1/2 hour from Waikiki. http://www.sealifeparkhawaii.com/
Very nice, little museum in a gorgeous estate with fine views about 2 miles from campus. There is a nice cafe and shop. Worth a visit! 2411 Makiki Heights Drive. http://honolulumuseum.org/11981-contemporary_museum_spalding_house/
Get a map. Allow most of the day, though not far in miles, the North Shore is slow driving, and you will want to stop. Perhaps best done counter-clockwise in direction. Get a guide book. Particularly spectacular in winter when high waves attract surfers from around the world (but watch out for huge fluctuations in wave height... never turn your back on the ocean). Pupukea Beach Park rivals Hanauma Bay for snorkeling, but do not go in during winter high surf. Waimea Arboretum, though a tourist trap, does have world class collections of plants and many endangered species from tropical areas around the world. http://www.aviewtoathrill.net/2009/11/25/navigating-oahus-circle-island-tour/
``Old Hawaii'', the one you saw pictures of in National Geographic Magazines as a child, does really still exist in some locations on the other Islands. One could write much about what to see, and many have done so. We will only make a few suggestions. First, get a good guide book. Second, get moving on reservations immediately. Our travel agent, can help you with package prices, which save considerably.
The three obvious choices are the Big Island (live volcanoes), Maui (extinct volcanoes), and Kauai (lush eroded volcanoes). They all have huge variation in microclimate as you circle the island. The higher elevations are cold, and there is even snow on Mauna Kea and Mauna Loa (14,000 feet). For warm dry sunny weather, stick to the Western and South-Western shores. If you can only visit one island, we suggest the Big one. It is larger than all the rest together, and the Volcanoes National Park is unique. The volcano is active and you can probably see flowing lava at the end of the Chain of Craters road.
You who have traveled widely probably do not need any cautions. Behave as you would in, say, Italy or Turkey, in terms of where you go alone or late at night, and guard your valuables. Some people consider anything left in rental cars (including the trunk) as fair game for redistribution. This includes crowded parking lots and remote beaches: do not leave any valuables in your car.
Much news has been made on the few occasions that tourists have blundered into someone's marijuana patch and been killed. If you are hiking on the established trails this will not happen. If you should be bushwacking (which we do not recommend anyway because the brush is incredibly thick), and come upon an unofficial agricultural endeavor, depart swiftly.
Information, including brochures, is available from Karen Rehbock at the Institute for Astronomy, Office C202, telepone 01-808-956-6829. See the IfA page on the WWW visitors.
You should take a 4 wheel drive vehicle in the winter. The only auto agency that rents vehicles with permission to go up the mountain is Harper's of Hilo, at 969-1468 (this may be out of date). They pick up at the airport or hotel, and are the agency that the astronomers commonly deal with.
The weather is always cold on the mountain top, particularly so in the winter. You may not be able to get to the top if there has been much snow; the road is sometimes closed. You should have proper winter clothes. Moreover 14,000 feet is quite difficult physiologically: you will be short of breath and you will not feel like running around. Nevertheless, anyone in reasonable health should not find it dangerous or even very uncomfortable. It is strongly recommended that no one under the age of 16 go up.