This was around 1515, not long before his passing. As yet I have not found drawings online of these, only the later (1578) Bourne Submarine based upon principles from it.
It was quite simply a shell, with space for one person to sit - and was designed as a "ship to sink other ships". It was actually only "Semi-Submersible".
Building Submersible Robots
Time to build your own robot! Using a Raspberry Pi with parts and some time, you can use my book to learn how to make and program a robot with automatic behaviours.