In position-based routing algorithms, the nodes use the geographical information to make routing decisions. Recent research in this field addresses such routing algorithms in two-dimensional (2D) space. However, in real applications, the nodes may be distributed in three-dimensional (3D) space. Transition from 2D to 3D is not always easy, since many problems in 3D are significantly harder than their 2D counterparts. This book focuses on providing reliable and efficient position-based routing algorithms with the associated pre-processing algorithms for various 3D ad hoc networks. The first part of this book proposes a constant time algorithms that construct an independent dominating set and connected dominating set of a Unit Disk Graph in a 3D environment. The second part of the book proposes an implementation of 3D versions of many current 2D position-based routing algorithms in addition of creating many new algorithms that are specially designed for a 3D environment. It has been showed that these new routing algorithms can achieve nearly guaranteed delivery while discovering routes significantly closer in length to a shortest path.