The last hole in The Loop is High (In). This hole is the basis for the Eden Template. The two bunkers guarding the green are the Hill bunker on the left, the Strath bunker just short, and the River Eden long. The hole is a test of whether the player can keep their ball below the hole.
The green here has a very strong back-to-front slope, which will help with stopping incoming shots. However, the flip side of this slope is that ending up above the hole is an absolute disaster. Putts can run completely off the front of the green. The Hill bunker prevents access from the side, but the front Strath bunker is the real challenge. With a short and middle pin placement, prevailing headwind forces the gamble of keeping the ball below the hole vs ending up in the Strath. It's an ideal test in it's simplicity.
Guarding back pins, the ground falls off steeply toward the Eden estuary, into a deep valley. Missing long can easily lead to double-bogey.
High hole in is the archetype for this Eden template, testing whether or not the player can safely leave the ball below the hole. It is one of the most interesting designs in golf.
"No green, however has a more perfectly fashioned entrance than the famed 11th hole at St. Andrews, the High Hole In. This green is defended on the right side by the deep Strath bunker, behind which the pin is usually placed on championship occasions. To the left the approach is open for some twenty yards. This entrance is just wide enough to lull the player into a sense of false security; if he aims safely from the Strath and pulls his iron shot slightly, he will surely find Hill bunker on the left of the green, where 19-year-old Bob Jones picked up in self-disgust in the 1921 Open Championship."
"I think the eleventh (the short hole coming in at St. Andrews) may be considered one of the ideal holes of the world... There is no hole that has been copied more frequently than the eleventh at St. Andrews, but I do not know any copy that has the charm, the interest, or the thrills of the original."
In 2015, the green was flattened significantly. Many architects, notably Tom Doak, came out publicly against these changes when they were announced in 2012.