The #42 bus will take you from Waikiki to the Arizona Memorial in ~ 1 hour.
The bus runs 2-3 times/hour.
It drops you at a bus stop on the circular driveway in the memorial grounds.
However, to catch #42 for the return to Waikiki, you must exit the circular driveway and turn left onto Kamehameha Highway to find the bus stop, which is around a half block away. Signage is poor to non-existent.
One way fare is $3.
Senior and student fares $1.50.
Cash accepted, but bring exact change as no change is given.