Carnival Cruise Lines plans to offer two California-to-Hawaii round-trip voyages next year and the year after.

The 15-day cruises will leave from Los Angeles in December 2011 and San Diego the following April.

Both voyages are expected to make daylong stops in Hilo, Kahului, Honolulu, Lihue, and Kona.

The Miami-based company said in a statement today the tours would provide “consumers with a more convenient and cost-effective means for visiting the breathtaking island chain.”

The cruises will mark the first time Carnival Cruise Lines has offered round-trip journeys to Hawaii.

The state’s cruise ship traffic has dropped in recent years after Norwegian Cruise Lines removed two of its three interisland vessels from Hawaii in 2008.