DARPA: Positioning System for Deep Ocean Navigation (POSYDON)

Innovative approaches that enable revolutionary advances in science, devices, or systems so that a Positioning System for Deep Ocean Navigation would provide omnipresent, robust positioning. No specified funding or duration. 

Areas of interest:

• Acoustic measurement modeling
• Acoustic source and waveforms
• At-sea data collection and demonstration
• Adjunct technologies (optional)

https://www.fbo.gov/?s=opportunity&mode=form&id=e17813912986c2371f37a62fce005b07&tab=core&_cview=0