From whale and dolphin watching, sailing and diving to discovering volcanoes and waterfalls, Hawaii Activities.com has more than 600 ideas for a fabulous vacation. Take the hassle out of planning your Hawaii adventure and book tickets for activities, tours and attractions online at competitive prices. Popular activities sell out weeks in advance; book early before you arrive in Hawaii to avoid disappointment. Ticekts, maps, itineraries, and directions are delivered free via e-mail or U.S. mail, to your home or hotel. Spend your time experiencing Hawaii, and leave the work of planning to professionals.

Guide Michael Walther has spent his life studying local flora and fauna, and he imparts his knowledge during these interesting eco-excursions. Invigorate yourself with an early morning hike to the 763-foot summit of the Diamond Head Crater. Visit magnificent waterfalls during the afternoon rainforest excursion in the Ko'olau mountains. There are several tours to choose from, as well as combination tour packages. Call for more details.

As one of the largest ocean activity providers on the island, Hawaii Nautical is your go-to for unforgettable adventures and memories that will last a lifetime. Hop aboard one of their vessels and get ready to dive into the crystal clear waters to discover the beautiful marine animals that call Hawaii home. From snorkeling with turtles through coral reefs, sunset sailing dinner cruises, whale and dolphin watching, to private charters, scuba diving, and fireworks, Hawaii Nautical has activities for the whole family to enjoy. This ocean adventure company operates out of various harbors on the island, so you'll be sure to find one close to you. Check out the website or give them a call to learn more about the seemingly endless options of seafaring fun.

Hula dancers greet each passenger as they depart on the largest of the local cruise ships, The Star of Honolulu. Visitors cruise off Oahu's leeward shore as the sun sinks below the horizon and the twinkling lights of Honolulu and Waikiki emerge in the dusk. There is always a live band and singers. Dine on a feast of steak and crab legs with a complimentary tropical cocktail.

Kick back and relax in an air-conditioned tour bus as a certified tour guide takes you around the notable points of Honolulu. There are nearly a dozen organized tours, a Waikiki Trolley day-pass and an option to design your own tour. Popular tours include the Pearl Harbor & Punchbowl Crater Tour and the Circle Island Beach & Dole Plantation Tour, which is a full-day excursion to all the most famous aquatic landmarks on the island. Call for more information.