Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

What was the largest dam removal project in history?

 The largest dam removal project in history was the removal of the Elwha Dam on the Elwha River in Washington state, United States. The Elwha Dam was a hydroelectric dam that was built in 1913 and was used to generate electricity for the Olympic Peninsula.

In 1992, the U.S. Congress passed the Elwha River Ecosystem and Fisheries Restoration Act, which authorized the removal of the Elwha Dam and the Glines Canyon Dam, a second dam downstream. The goal of the project was to restore the natural ecosystem and fisheries of the Elwha River, which had been severely impacted by the dams.

The removal of the Elwha Dam began in 2011 and was completed in 2014. The removal of the Glines Canyon Dam was completed in August 2014. The two dams were removed using a combination of explosives, cranes, and heavy machinery, and the process was carefully managed to minimize environmental impacts.

The Elwha Dam removal project was the largest dam removal project in history in terms of the size of the dams and the amount of concrete and steel that was removed. The project was also significant because it marked the first time that a dam of such a large size had been removed in the United States. The project has had a number of positive impacts on the ecosystem and fisheries of the Elwha River, and it has been widely hailed as a success.