Hi,
It was clear that the Gaza strip is full of tunnels. It started with the smuggling tunnels from Egypt to Gaza strip under Philadelphi Route before the disengagement 2005.
Those were used for anything to get inside Gaza strip: sheep, fuel, brides, and so on.
During the years, many attack tunnels were found inside Gaza strip and along its border with Israel. Many were destroyed during Operation Protective Edge, and also during operation Guardian of Walls.
The Israeli conception that collapsed on October 7th was that Hamas would use its attack tunnels to send a small number of terrorists into Israel. And that the underground obstacle along the border will reduce the number of tunnels or prevent all of them. Instead, Hamas‘ attack was in big numbers and above ground, penetrating many places along the border fence.
The tunnels are a major threat of IDF soldiers inside the Gaza strip. It allows Hamas terrorists to suprise the forces and them from behind.
The biggest tunnel found was big enough for even a car to drive through it, a video of the brother Hamas leader, Yahya Sinwar, driving through it was found.
A large tunnel was even found underneath Shifa Hospital, connecting it to other terror locations around it and probably used to hold or transfer the hostages.
The joke was that Hamas can build those so fast and good, why noylt to give him to built the tunnels of Tel-Aviv light rail tunnels, so they can finnaly open.
In the north of Israel, on the border with Lebanon, there were also attack tunnels. For years, the citizens along the border complained about vibrations and digging noises underneath their houses. As the ground along the border is Limesone, it was considered unreasonable that Hezbollah will chiesel tunnels in it.
But in 2018, in Operation Northern Shield, IDF found and destroyed 6 attack tunnels along the border. Hezbollah idea was to penetrate Israel through those tunnels and take over Israeli settlements (just as Hamas did on the Black Sabbath)
Take Care
Gad
The biggest tunnel revealed in Gaza strip: 50m deep and more than 4 km long (Source: idf.il)
The tunnel underneath Shifa Hospital
The explosion of a tunnel grid underneath Hamas commanders quarter
Visualization of Hamas underground infrastructure structure underneath civilian sites
The inside of Ramia tunnel from Lebanon to Israel in May 2019, it was 80m deep (as a 22-storey building), and it penetrated 77 inside Israel and was destroyed (Source: Wikipedia.org)