A dry dock is a hole in the ground that pretends not to be next to the sea. Jan Blanken's challenge at Willemsoord was simple to state and impossible to execute: hold back the North Sea, the tides, the groundwater, and the polders, all at once, all the time, with brick and mortar and one steam engine. Construction of the pump building began in 1813, then stopped, then resumed in 1816 after Dutch independence had been restored. When the workers came back they could not find the thirty piles they had driven into the ground three years earlier. The piles had vanished. Iron sounding rods called peilijzers turned up nothing. The well that destroyed them was still working. Heavy fir beams were laid across the void at eighty-centimetre intervals, the gaps closed with brickwork, a second layer of beams laid crosswise, and the whole levelled into a foundation through sheer stubbornness.

In April 1817 the tender went out for the dry dock pit itself. Conditions in the dock proved worse than under the pump building. Three chain pumps ran day and night against a slurry of sand and water. Thirty work horses fed on premium rations died in the harness. The walls of the pit slumped into beach-like slopes. And yet the pile driving succeeded, the connecting beams were laid, the floor was levelled by hacking and filling. The brickwork went up around 6,124 cubic feet of blue Petit Granit stone shipped from Écaussinnes in southern Belgium. By July 1822, twenty-three feet below high tide, workers were laying the blocks that would receive the keels of ships.

On 13 July 1822 the ship of the line Willem I, seventy-four guns, formerly the French vessel Couronne, was steered into the new dock. The water was pumped out. The Willem I settled on her blocks with her full weight bearing down on the brick floor, and the floor held. Authorities exhaled. The new dry dock had done what similar docks in France and England had famously failed to do. The early reports were also wrong. The well that had soaked the workhorses was still down there, still connected to the sea. While Willem I sat on her blocks, the dock floor lifted eight centimetres under her keel. Her weight made no difference. The water was winning, slowly, the way water always wins.

The 1826 commission diagnosed the problem precisely: when the dock was empty, the floor levitated by 9.4 centimetres at exactly the point where a ship's mizzen mast would stand. Proposed fix was twenty-six oak beams, sixty-three centimetres thick, clamped to the foundation. Cost estimate, 59,297 guilders. The contractor demanded 129,642. A subsequent plan from engineer D. Mentz to break out the floor and rebuild it as a brick inverted arch came in at 399,949 guilders, was approved, then quietly killed by the Dutch financial crisis of 1832. So they did nothing. They simply piled more iron ballast in the dock, eventually 653 last of it, to hold the floor down. Despite the leaks, Dry Dock I docked 120 warships between 1822 and 1849. In September 1848 the frigates Prins van Oranje and Sambre were serviced together in five days with their guns still aboard. Then in April 1849 the razeed frigate Algiers was inside when so much water came past the door that the pumps could not keep up. The dock was finished.

The first attempt to fix the lock alone, between 1853 and 1854, made things worse: water was now flowing under the foundations themselves. Wooden pile screens driven north and south of the lock failed. By 1857 the floor near the lock had been pushed up fifty-one centimetres on one side and sixty-two on the other. A crack thirteen metres long and seven centimetres wide ran through the dock floor. The Algiers, still inside, was sold for scrap where she stood in 1853. The decision was made to demolish almost everything above the foundations and rebuild. Construction restarted on 17 March 1859. Workers found that the failed pile screens were perfect at the top and shattered at the bottom. They poured a concrete coffer around the outside of the lock, drove new screens, packed 332 cubic metres of sand under the lock walls with long pestles, then poured a new brick inverted arch as the dock floor, this time with iron eye bolts to keep the wooden ship blocks from floating up when the dock filled. By late October 1860 the last brick was laid.

The new caisson, the floating door that sealed the dock, was a marvel from England. Iron throughout, 122,513 kilograms total weight, of which 103,537 kilograms was iron resistant to shipworm. Inside the hollow door, balance gates and gate valves let water in to ballast it down; four pumps driven by a six-horsepower portable steam engine called a locomobile could pump it out and float it up in twenty-two minutes. Tugged from Hellevoetsluis on 7 April 1861, the caisson arrived the next day, was tested, and proved leaky everywhere the balance gates were supposed to seal. The caisson was taken into service anyway in October 1861. One balance gate was eventually replaced by a sliding mechanism in May 1863, and that finally fixed it. On 26 October 1861 the steam frigate HNLMS Wassenaar entered the rebuilt dock at 10:30 in the morning. By 4:10 that afternoon she was sitting dry on her blocks. The dock was alive again.

Dry Dock I currently measures eighty-five metres long by twenty-five metres wide on its rim, narrowing toward the floor, about four metres deep. Since 2005 it has held HNLMS Bonaire, a Samarang-class screw gunvessel launched in 1877, undergoing a restoration as ambitious as the work on HMS Warrior in Southampton. Bonaire is the same ship that bobs in the wet dock photographs of Willemsoord, but inside Dry Dock I she sits high and dry on the blocks, her hull exposed in cross-section, plating coming off and going back on. It is a strange continuity. The dock was built to maintain wooden ships of the line under sail. Two hundred years and one full rebuild later, it is still doing maintenance, on a ship from the steam age, for a country that no longer needs warships out of Willemsoord. The water table beneath, presumably, has not given up either.