It depends upon which cruise line you choose cause not all cruise liner provide on-board cellular services. Some provide this service and the shipboard services gets automatically activated when the cruise drifts away from the range of land based cellular tower while some cruise restricts usuage of mobile phones
Well i am not sure about Hawaiian cruises but i do know about WMS network which provides very cheap roaming services on all major cruise to wireless carriers worldwide like Roger wireless, T-Mobile, 3, Vodafone etc. Please make sure your carrier has an agreement with your ship or else your usage will be charged as per their proposed international roaming rates. Hope this helps you.