The Glock 17 is the most widely used pistol made by Glock. It's a 9mm pistol, and was designed in 1980 by Gaston Glock. The Glock 17 uses Glock's trademark polymer construction, so while the gun is lightweight, it still has a 3 ton crush weight; the synthetic is actually stronger than steel while being 86% lighter. The G17 is constructed from a steel slide mounted on a polymer frame with alloy inserts. It's also noted as a highly reliable gun, probably due to its low number of parts - a total of only 33 individual components.
The Glock 17 is noted for enduring a severe set of torture tests. Glock wasn't nice to their gun during testing, however the G17 survived every test. In one test, the gun was filled with sand and subsequently fired. It managed to fire the round with no problems. In another test, the Glock 17 was frozen in a block of ice, chipped out, and fired. Again, it fired without a hitch.
For evaluation by the U.S. Navy SEAL Team, a modified firing pin assembly was constructed for the Glock 17, and another test was conducted by firing the gun underwater. Only the Glock 17 was intended to use the modified assembly for aquatic firing, and was explicitly designed to fire while fully submerged underwater. So while any Glock will fire underwater, doing so improperly can generate excessive internal pressure causing the pistol to, quite literally, explode - taking your hand along with it. Don't do it.