I've not toured Hawaii with RCCL but most ships offer very similar tours.
Off of NCL Wind a few years back we took an excellent and very comprehensive all day our . It was pitched as an "eco tour". We were picked up in vans and driven inland to
an orchid farm . We had a tour and the whole process was explained. From there we drove through the lava fields to Lava Tree State park We got to see effects of lava and eruptions up close. (although no active volcano here any longer). Third stop was combination lunch and snokelling in a lava inlet fed by sea water and fresh water from under ground. Snorkelling included literally crawling over some hard lava to access a most beautiful and pristine coral garden with huge brain corals as the feature. Fourth stop was a natural, lava heated hot spring pond where we relaxed in 100 degree water.
Final stop was a breif stop at Hilo Hatties for anyone who needed to shop. The tour was basically all day.
Check out if something similar is offered .