Large and famous cliffs

Given that a cliff need not be exactly vertical, there can be ambiguity about whether a given slope is a cliff or not, and also about how much of a certain slope to count as a cliff. For example, given a truly vertical rock wall above a very steep slope, one could count only the rock wall, or the combination. This makes listings of cliffs an inherently uncertain endeavor.

Some of the largest cliffs on Earth are found underwater. For example, an 8000-meter drop over a 4,250-meter span can be found at a ridge sitting inside the Kermadec Trench.

The highest cliff (rock wall, mountain face) in the world, is Nanga Parbat's Rupal Flank, which rises approximately 4600 meters, or 15,000 feet, above its base. According to other sources, the highest cliff in the world, about 1340 m high, is the east face of Great Trango in the Karakoram mountains of northern Pakistan. This uses a fairly stringent notion of cliff, as the 1340 m figure refers to a nearly vertical headwall; adding in a very steep approach brings the total height to over 1600 m.

The location of the world's highest sea cliffs depends also on the definition of 'cliff' that is used. The Guinness record books claim it is Kalaupapa, Hawaii, at 1010 m high. Another contender is the north face of Mitre Peak, which drops 1683 meters to Milford Sound, New Zealand. These are subject to a less stringent definition, as the average slope of these cliffs at Kaulapapa is about 1.7, corresponding to an angle of 60 degrees, and Mitre Peak is similar. A more vertical drop into the sea can be found at Maujit Qaqarssuasia (also known as the 'Thumbnail') which is situated in the Torssakutak fjord area at the very tip of South Greenland and drops 1560m near-vertically.

Considering a truly vertical drop, Mount Thor on Baffin Island in Arctic Canada is often considered the highest at 1370 m (4500 ft) high in total (the top 480 m (1600 ft) is overhanging), and is said to give it the longest purely vertical drop on Earth at 1250 m (4,100 ft). However, cliffs on Baffin Island, such as Polar Sun Spire, or others in remote areas of Greenland may be higher.

The highest cliff in the solar system may be Verona Rupes, an approximately 20 km (12 mile) high fault scarp on Miranda, a moon of Uranus.