Which side of the ship?

Hi. Wondering if it matters which balcony side should we choose for viewing the transit through the locks? Thanks.

It doesn't matter. To really see the Canal, you should not be planning to stay on your balcony all day. You need to be out and about, watching from different locations. As commonly recommended here, being on the bow (if your cruise line allows it) as you enter a lock or two, is impressive. Being on the open, low promenade deck ( if your ship has one) during a couple of locks is also great.

Thank you.

Bruce's advice is exactly what I would recommend. I also would add that during your crossing of Gatun Lake (Atlantic to Pacific) I think the view from the port side is a wee bit more interesting since that is the best chance to view on coming ship traffic. Coming the opposite direction on coming ship traffic is on the port side as well, but you will miss somethings I would not want to miss if you were to stay on the balcony a lot.