But even if we went with the same 80 year old designs of bombs as in world war 2, the biggest challenges with Operation Chastise has been solved today by the user of precision-guided munition, drones and cruise missiles. The pilots of Operation Chastise had a major challenge flying so low, with such a heavy payload, with a very narrow target window, using technology that was neither precise nor easy to use. They could also not avoid flak from anti-air, and the explosion from the bomb was a major threat to the plane forcing the pilot to balance their own and crewmen life with that of the mission. Misty weather also prevented one plane from even find their target. It was a very risky mission.
There are three basic angles of attack, from the front, top, and water. Anything that comes in from the front or top and then detonates has a large hole to let energy back out without damaging the structure. The same issue also applies to a water entry with current perpetrators as these things are designed for high speed impacts which creates a large void behind the bomb.
Ideally you want something that lands in exactly the right spot and then slowly sinks to the right depth. And of course no netting to be around the dam to make the mission that much more difficult. Which gets back to my previous point, it’s clearly possible, just technically difficult.
If look at the actual dams from WWII you notice they all got damaged about half way up and only blew out a section of the dam. This is because thickness increases dramatically with depth and bombs only have so much energy. They needed the pressure of a dam at near maximum capacity to work, which is why several other dams services just fine.