1. A method of estimating position and orientation (pose) of an underwater vehicle comprising: receiving pose data from one source; receiving pose data from another source, the data from the another source is correlated with the data from the one source; combining the data from the one source and the another source, the combination resulting in a fused pose estimate; determining whether to generate a forward prediction of the data received from either the one source or the another source, and generating the forward prediction if needed; and determining an updated pose of the underwater vehicle based on the fused pose estimate; and determining when to and updating the one source or the another source based on the fused pose.