HAWAII has 6 major islands, with 4 of them being well visited and populated. These 4 are Maui, Kauai, Oahu (where Honolulu is located) and the “Big Island” itself, named Hawaii. Hawaii has an unusual set of circumstances that impacts cruising there. Due to an obscure law from about 100 years ago that the Cruise industry is trying to repeal; only US built cruise ships with US staff and flagged in the US are allowed to leave a US port and return to a US port on the west coast (This is why one way Alaskan cruises always stop or end in Vancouver instead of Seattle).
Currently only Norwegian Cruise Line is the only mainstream ship that leaves from Hawaii and returns to Hawaii. Their ship “Song of America” offers 7 night cruises year-round in and out of Honolulu, stopping in three other ports on other islands. This sailing is quite a bit more expensive than a comparable sailing on a similar ship elsewhere such as the Caribbean, as the affiliations with the US as described makes it so.
Other than this ship, other mainstream cruise lines will start or end in either Mexico or Canada and go one way either to or from Hawaii. This can give you the same amount of time in ports of call as the Song of America, however it is a much longer journey with 4 or 5 days added on for the days at sea necessary.
Un-Cruise is a niche cruise line with small ships carrying less than 100 passengers. They have a US built, flagged and staffed ship that has unique itineraries throughout Hawaii, starting and ending there, eliminating the lengthy cross Pacific crossing between Hawaii and Mexico or Canada. These are typically about twice the cost of the NCL cruise, however well worth it!!