Aiea Loop Trail is a 5 mile beginner/intermediate level hike located on Oahu. It's a relatively flat trail, with some hill climbing, stream crossing, awesome views, and lots of mud... or at least on the day I went.
A group of 17 of us went out around 9:15am and finished the hike about 1:45pm! It took much longer than the 2 hours that was expected because it was raining off and on all day which made the trail pretty muddy and slippery in come areas. Plus, the group that went ranged from advanced hikers to total beginners, which meant a lot of waiting around for the back end of the group to catch up. No big deal since I had nothing else planned for the day. =)