Sea Wave and stream measurement with NB-IoT project

I am looking to deploy an NB-IoT system to measure and collect data on wave and stream movement from a sea float. No existing sensors or equipment will be used. The data will be collected by a server and in a later time that data will be processed by clients computer. We are contractors and our client needs one prototype only. This will not be a production project.
The sensor are required to be Ultrasonic for the wave height meassurement (up to 5 meters is enough). The other two senors that will define stream velocity and stream direction need design. We do not think that exist ready made for marine use (should withstand salt).
The data from the sensors will be transmitted with a NB-IoT modem to the server (this should be setup with the appropriate program).
If you feel confident that you could develop a system to fulfill these requirements, I’d appreciate your assistance. Thank you.