  We analyze the problem of localization algorithms for underwater sensor
networks. We first characterize the underwater channel for radio communications
and adjust a linear model with measurements of real transmissions. We propose
an algorithm where the sensor nodes collaboratively estimate their unknown
positions in the network. In this setting, we assume low connectivity of the
nodes, low data rates, and nonzero probability of lost packets in the
transmission. Finally, we consider the problem of a node estimating it's
position in underwater navigation. We also provide simulations illustrating the
previous proposals.
