Mobile ad-hoc networks are infrastructure-free networks of mobile nodes that communicate with each other wirelessly. There are several ad hoc routing algorithms at present that utilize position information (usually in two dimensional terms) to make routing decisions at each node. We consider routing algorithms that use 3D positional information, particularly a hybrid extension to LAR that works in 3D. We propose a new hierarchical, zone-based 3D routing algorithm, based on GRID by Liao, Tseng and Sheu (2001). Our new algorithm called "hyper-GRID" is a hybrid algorithm that uses multipath routing (alternate path caching) in 3D. We propose replacing LAR with multipath LAR (MLAR) in GRID. We have implemented MLAR and are validating MLAR through simulation using ns-2 and studying its efficiency, scalability and other properties. We use a random waypoint mobility model and compare our MLAR approach versus LAR, AODV and AOMDV in both 2D and 3D for a range of traffic and mobility scenarios