The serious Mexican Riviera cruises are seven-day cruises on larger ships. Once again, the spotlight is on the three mega-ships mentioned above. These state-of-the-art cruise ships, each offering plenty of onboard activities to keep you amused for a week have prices that are extremely competitive. They all offer seven-day cruises to Puerto Vallarta, Mazatlan and Cabo San Lucas, known as the Mexican Riviera. Here is rundown on these ships:

Mariner of the Seas is in the Voyager-class and is the largest ship running regular cruises from California. Coming in at 138,000-tons and 3114 passengers she is the Queen of California cruising. She leaves Los Angeles on Sunday nights. This ship has offers rock-climbing, ice-skating, ice shows, Johnny Rockets, a Royal Promenade, production shows, inline skating, mini-golf, great children's programs, internet access, alternative dining, a sports bar, casino, nightclubs, karaoake, a spa and more. Prices this fall start at $477 pp, $748 balcony. Royal Caribbean gets the top rating in onboard activities.

Carnival Splendor is the competition. Not as big as Mariner but much newer, Splendor is as fun as a Carnival Fun ShipTM can get. At 113,000-tons and 3000 passengers, she was introduced just last summer making her the newest Carnival ship sailing. She makes Long Beach Harbor her home - right next to the permanently moored original Queen Mary. Splendor has everything Carnival offers; 22 bars and lounges including a sing along piano bar, the White Hot Disco, great production shows, great comedians, an outdoor movie screen by the pool, water slides, alternative dining, a multitude of surprisingly delectable food options, a spa, hot tubs, karaoake, Internet access, and more. Prices start at $439 pp, balconies for $729. Carnival gets the top rating in entertainment.

Sapphire Princess is the last mega-ship coming in at 115,875-tons and only 2670 passengers. This is the more premium option of the three mega-ships. Sapphire, sailing from Los Angeles, is a large ship with a smaller ship feel. The decor is less whimsical and more classic. The cabins are roomy with generous bathrooms and the pool deck offers hot tubs and a swim against the current pool. There is mini-golf, Internet access, karaoake, a piano bar, sports bar, an outdoor movie screen, plenty of live music, a wine bar and an extensive wine collection. Princess gets the top ratings in personalized service.