You could probably get there with a boat - somehow - but an airplane is definitely the preferred way to get to Iceland from the United States. And if you're coming in by air, you're coming into the wonderful Keflavik International Airport [KEF]. Feel free to use the airline of your choice, but two that you may not know about are Icelandair and WOW air. Both fly out of Pittsburgh (which is relatively nearby for some of you) and Wow air even provides direct flights straight from PIT to KEF.
Also, be aware most airlines feature group rates once the traveler count gets up there. For instance, Icelandair considers a group to be 10+ people, while WOW air uses 12+. Feel free to start a discussion here to talk with other guests to coordinate travel.
Oh, and don't forget your passport!