Hey Jim,
I have the Fold-a-cover made by K-Cover. I love it. It is able to fold towards the front of the bed and it can be locked down and secured. You can enter the bed by folding one section from the cab side or from the tailgate side. The whole lid can be removed by unscrewing 2 screws and can be removed by one person. It is for the most part water tight. You would have to spray a hose directly at the side of the lid or the spaces next to the tailgate for water to get in to it. If you are going to buy a Titan, I would suggest looking in to this cover. I think its at
www.k-cover.com
Good luck,
Eric