There is no better way to learn robotics, machine learning, and electronics than building your own things. The n3m0 Autonomous Boat is a robot boat with 3D printed parts. It uses the ArduPilot system to operate autonomously. It comes with temperature, salinity, and depth sensors.
The boat consists of a steering servo, RC receiver, GPS, power module, battery, telemetry radio, and other smart components. You can find out more about the project here.