The Falkirk wheel is quite an immense structure, but each one of it's basins is only 80m long and 6.5m wide. It's moving 500 tonnes of weight each rotation (split between the two basins to keep it balanced).

To service the Panama Canal, you'd need basins 370m long and 50m wide. The new Panamax ships are apparently capable of carrying 120,000 tonnes of weight (no idea what they weigh themselves), but we're talking about swinging around half a millions tonnes of weight. My brain can't comprehend that... are there _any_ moving structures of that size in the world?