Learn the basic principles of an ammeter, an instrument that measures electrical current:
Learn how to use the ammeter function of the NI ELVISmx Digital Multimeter ("DMM" on the NI Instrument Launcher) as implemented for the NI myDAQ:
One of your allied submersibles travels across the ocean without communication and rises to the surface at regular intervals of three hours, but at locations that are essentially random. The goal is to be in the right place at the right time for a certain meeting that is scheduled for exactly six days from now.