The difference in level between the oceans at the canal isn't very large. (Like 20 cm ?, and largely due to differences in tides and so on.) Instead, the boats are raised much more through the lock system while passing through the canal (Like 25 m ?).
Joao G.R. Poco , Probably because the levels of the oceans are dependent on tides, winds, on so on, there is variation in the reported values for the difference in the oceans at Panama. I've been finding much smaller values. ... But the point remains: the difference in level of the oceans is small relative to the elevations in topography when crossing Panama. It's difficult to imagine making practical use of the differences in level of the oceans. Especially considering that there are places around the globe that have large tide differences, waves, or perennial rivers.