Actually, the introduction of the concept of watercraft is interesting to me. It shows that the Sea of Simulation is not as inhospitable as it might have been presented. It illuminates that the Sea has a series of diversities which may extend well beyond (or entirely outside of) the behaviours we view bodies of water as possessing.
Moreover, I joke, it's not static and flat at all, unlike
Reboot, where anything unprotected (or otherwise not made for water travel) which touches that universe's oceans is simply deleted or destroyed. :P
Further, the Sea of Simulation is a widely unexplored medium. (Please correct me if I am wrong) It was said that ISOs emerged from the Sea, and the Sea was later poisoned by Clu in order to stop the manifestation of ISOs. Exactly when this occurred in the timeline, I am not certain - but Tesler's place by the Sea could easily have been to observe testing or execution of small-scale procedures, or to test the far shores of Argon to see whether the Sea of Simulation was still 'regulated' effectively.
There might have been wreckage or important Program-created artifacts or energy sources which Tesler wished to see for himself - he is an ambitious Program, and a chance to seize resources which to claim as his own would likely be a prerogative.
Also, if vehicles as vast and powerful as Tesler's command ship - or greater! - can be created, it opens the way for naval activity, underwater bases, architecture, and even floating cities or military constructs! All fascinating possibilities... Especially considering how they might interact with the strange and mysterious qualities of the Sea of Simulation!
I'll just ignore the rest of that activity of yours, Moses.