Catalina Express (tel: (800) 481-3470) is the most popular way to get to Catalina Island via their fleet of boats. In the summer months, Catalina Express offers about 30 trips a day to Avalon from San Pedro, Dana Point and two ports in Long Beach, downtown and at the Queen Mary. If you're on the west side or north of LA, the Marina Del Rey Flyer is your best bet.
Catalinaferries has two boats making trips daily in the summer and also have a special winter schedule. It's a great way to get out of town without having to drive out of town.
Perhaps the best way to reach the island is by private sailboat or powerboat, about a half-day from the Los Angeles harbors. The seas in the channel are generally calm, tho there are swells; dolphins and other sea life are often sighted.
Around Avalon, the primary mode of transportation is by golf cart. The streets are very narrow and the town is crowded and small so this works out very well. Upon arrival to Avalon by sea you will see signs for golf cart rentals.
For the day visitors, there are city and island Discovery Tours and Catalina Adventure Tours.
You may also rent bicycles (or bring your own from the mainland for an extra fee).
Brown's Bikes - 107 Pebbly Beach Road. Tel: +1 310 510-0986, fax: +1 310 510-0747, e-mail: email@example.com. Rentals and bike repair. Hourly rates are from $5 to $15 per hour, depending on the type of bike. Daily rates are from $12 to $40.
Catalina Auto & Bike Rental - 301 Crescent Avenue. Tel: +1 310 510-0111. Bicycle and golf cart rental.
Wrigley Memorial and Botanical Garden (tel: +1 310 510-2595) - 1.5 miles (2.4 km) up Avalon Canyon Road from Avalon. Daily from 8AM to 5PM, year round. A memorial to William Wriggley, Jr., founder of the WM Wriggley Jr. Company, renowned for its chewing gum. Mr. Wriggley was also a long-time benefactor of Catalina and was key in assuring that it was protected for future generations. The Botanical Garden features plants that are native to California islands, especially species only found on Catalina Island. Adults: $5, Children under 12: Free.
The Casino/Art Museum (tel: +1 800 626-5440) - Casino Point, northwest end of Avalon Harbor. The Casino is an Art-Deco movie palace and ballroom built in 1929 that was once the place to be for the Los Angeles elite. The tour will take you into the movie theater and up the ramps to the ballroom while the tour guide gives information about the history and unique construction of the casino. Adults: $14.50, Children: $7.25, Seniors: $13
Descanso Beach Club - On the north side of the casino. (Tel: +1 310 510-7410). A beach front bar and restaurant. Showers, chair and umbrealla rentals and restrooms are available.
Catalina Island Museum - Ground floor of the casino building. Tel: +1 310 510-2414, fax: +1 310 510-2780, e-mail: firstname.lastname@example.org. April – December: Open every day of the week, 10:00PM – 5:00PM Closed Christmas Day. January – March: Closed Thursdays, Open Friday – Wednesday, 10:00PM – 4:00PM Permanent exhibits display the history of Catalina from the early Gabrielinos through Catalina's heydey as a playground for the rich and famous. Special exhibits change regularly. Adults: $5, Seniors: $4, Children (ages 6-15): $2, Children under 5: free
Multiple locations. With warm temperatures and clear waters with visibility from 40-100 feet (12 to 30 m), Catalina is a prime location for snorkeling and scuba diving. Several vendors rent equipment or provide guided trips.
Lover’s Cove Undersea Gardens - Just a few minutes from the boat landing in Avalon, this cove features giant kelp forests and hundreds of fish. Tel: +1 800 766-7535.
Descanso Beach - Just north of the Casino. Rental equipment available. Tel: +1 310 510-1226.
Casino Point Marine Park - At the edge of Casino Point. Artificial reefs, a kelp forest and shipwrecks provide opportunities to explore.
Scuba Luv - 126 Catalina Avenue. Toll free: (800) 262-3483, phone: +1 310 510-2350, fax: +1 310 510-0821, email: email@example.com. A complete scuba outfitter providing rentals, instruction and guided trips from their 65-foot (19 m) dive boat King Neptune.
Catalina Divers Supply - Green Pier and Casino Point. Toll free +1 800 353-0330, phone: +1 310 510-0330, fax: +1 310 510-1629, e-mail: firstname.lastname@example.org. A complete scuba outfitter providing rentals, instruction and guided trips from their 42-foot (12 m) dive boat Cat Dive.
Annual Avalon Harbor Underwater Cleanup. An annual event where scuba divers dive in Avalon Harbor to remove trash and other items from the floor of the harbor. This is the only day of the year that scuba divers are allowed to dive in the harbor.
There are a variety of places to eat on the pier, serving things like hot dogs and fish and chips. There is also a small Vons supermarket at 123 Metropole Avenue which may be helpful if you need a candy bar, soft drink or such.
Ristorante Villa Portofino, 101 Crescent Avenue, (310) 510-2009 
Catalina Visitors Country Club , (310) 510-7404 
Aurora Hotel & Spa, 137 Marilla Ave, ☎ (800) 422-6836, . checkin: 3 PM; checkout: 11 AM. Romantic modern hotel & spa in beautiful downtown Avalon. Book Luxurious rooms & amazing suites at this Catalina Island luxury hotel.$150-$925. edit
If you are coming from the mainland you probably want to see a bit more of Catalina Island, such as Two Harbors or the interior of the island (home of the buffalo). Unfortunately, since golf carts are not allowed outside of Avalon, you are pretty much trapped, as roads leading away from the town hold "no golf cart" signs. So, if you are interested in visiting other parts of the island, another mode of transportation (such as bicycles or perhaps a small motorscooter) must be found. Note that Santa Catalina Island is hilly so you might find yourself pushing your bike up the roads in the island's interior.
This is a usable article. It has information for getting in as well as some complete entries for restaurants and hotels. An adventurous person could use this article, but please plunge forward and help it grow!