Not quite what you are looking for, but I'd like to bring up the Dutch Waterlinie. This was basically a system of waterways that, in the event of enemy invasion, could re-inundate a large part of the country, effectively making Holland into an island. It was also used during the 80 years war as an offensive weapon to break sieges, by inundating the surrounding countryside where the Spanish army was camped around Haarlem and Leiden.

Yes. The biggest example of using this was the scuttling of the interned German High Seas Fleet at Scapa Flow following WW I (see Grand Scuttle by Dan van der Vat). The means to do this involved sea-cocks and pumps which also had other purposes, so it was not a dedicated facility, but scuttling a ship by these means had long been known as a tactic to avoid an enemy coming into possession of a resource (hence the existence of the verb in English), and in some vessels this was part of the training - WW II U boats, for instance.

Switzerland is apparently heavily mined at bridges, passes and tunnels in preparation for an invasion, which might be more what you were looking for.

In the age of gunpowder, it was not uncommon for retreating armies to detonate their powder stores, denying its use to enemy forces. This often had the effect of rendering the forts where they were stored unusable.

At the Battle of York in western Canada in 1813, British forces rigged their fort to explode while ostensibly negotiating surrender. 38 Americans died in the explosion, including Brigadier General Zebulon Pike.

The US created atomic demolition munitions. These were atomic bombs stored in strategic locations and detonated in the event of a NATO withdrawal to prevent the facilities being used by Warsaw Pact forces