Birthday ideas in hawaii during honeymoon?

I am getting married Oct 1st 2011 and my future wife and I will be honeymooning in Hawaii. We will be going to Oahu & Hawaii (The Big Island). We are going to be in Oahu from Oct 3 thru Oct 7, staying at the Turtle Bay Resort. My future wife's birthday happens to fall during our honeymoon. Her birthday is Oct 4th. So I want to do something special because her birthday is just as in important as the honeymoon itself so I don't want to downplay her birthday. I've been looking online and can't come up with something really special, i was hoping that someone could help me out, either people who have been in this situation or who know great little ideas for something special. I thought about asking when we get to the hotel but really don't know what they can come up with. Maybe someone knows if that specific hotel can do something nice or I am open to all ideas. We will have a rental car the whole time we are there so as long as its on Oahu we have no trouble getting somewhere.