The South Point complex was used as a look out for enemy fighters from Japan over the Pacific who might make contact with Hawaii, or the western United States. It was also used even before that as a shipping point for many good as they could easily be dropped off the side of the cliff, into the boats below with little effort as the deep shore line made it possible for large ships to come close to shore. The cliffside jump outs used to be ladders to the ships below. And the spikes here were used to hold the ships from the currents. Ka Lae, the most southern point of the Big Island of Hawai'i and of the 50 United States. The Ka Lae area is registered as a National Historic Landmark District under the name South Point Complex. The area is also known for its strong ocean currents and winds and is the home of a wind farm. This place has benchmarks, geocaches, windmills, houses, fishing, Cliffside, and dangerous jumping. Plaque says "Under the provisions of the historic sits act of August 21st 1935 this site possesses exceptional value in commemorating and illustration the history of the United States."
The following is from my earthcache.
Here is a snapshot of what you will see when you arrive!
Also please read these rules for the open space park and respect them so that others that come in the future may enjoy the South Point Complex as much as you did. 
Just take the main road down from Route 11 and follow all the signs to South Point Complex. 
Aloha and welcome to the Big Island of Hawaii and the southern-most geocache in the United States! I've been to the Big Island two times and this is my first time to the South Point Complex and thought it would be a great place for an earthcache.
"The name for the southern tip of the island of Hawaii comes from Ka Lae in the Hawaiian language which means 'the point'. It is often spelled as one word, Kalae, or called South Point or South Cape. A confluence of ocean currents just offshore makes this spot one of Hawaii's most popular fishing spots." The cliffs were helpful for to the United States its wide range of lookouts over the Pacific ocean.
Millions of years ago these cliffs were not here. In fact they used to run into the ocean but a much more south. The reason for this is called erosion. Erosion is the process by which the surface of the earth is worn away by the action of water, glaciers, winds, etc. In this case it is caused by the oceanic water (Halaea Current) and wind. The listed coordinates used to be much farther inland. The cliffs have a drop off zone of about 50 feet. If you walk over to the nearby South Point Cache you will see how the cliffs get smaller. One of the questions will have to do with the creation of the cliffs.
Wind Erosion: Wind erosion is caused when wind is blowing in a specific area and a specific speed until it is blocked by something like rocks and over millions of years that rock is broken into smaller rocks like sand and carried away by gravity. The sand will eventually turn into sediment. There are many windmills about three miles north of here on the cliffs. The many windmills serve as a major power house for much of the island. As you walk around the South Point Complex, be sure to look at the plants. They are bent in the direction of the wind. A good example of this is at the Anza Borrego State Park in Southern California. Picture can be seen below.
Wind Erosion Diagram 
This picture shows the Anza Borrego Wind Caves in Southern California. This is what happens when wind is the main cause for erosion. 
Water Erosion: Water Erosion is caused when water is costanly washing against something like rocks and carries the washed away sediment down stream or into the ocean. The sediment that you can see on the cliffs have different layers of rocks. Look at the cave for questions 2-4, you can see water inside of it. Every few seconds, you can see the waves crassing on the walls of the cave. This is water erosion happing right before your eyes! Fast forward 100 milion years and this place would be underwater and the most southern place in the United States will be to the east becuse of the volcanic ativity on the eastern side of the island I don't recommend swimming without a lifejacket due to the current "Halaea Current" named after a chief who was carried off to his death. If you walk along the cliffs at a very safe distance, the coast line here is very hard to get to without a built in ladder. The best example of this is probably the Grand Canyon in Northen Arizona. Picture can be seen below.
Water Erosion Diagram 
This picture shows the Grand Canyon in Northern Arizona. This is what happens when water is the main cause for erosion. 
As you can see, there is a distinct difference from both the water erosion of the Anza Borrego Wind Caves and the water erosion Grand Canyon. The Anza Borrego Wind Caves are more scatters and rugged terrain with ups and downs all over as the wind hits it from all different angles depending on the weather conditions. The Grand Canyon is also rugged, but with mostly down patterns due to the Colorado River. Here at the South Point Complex cliffs both amazing forces of erosion are the cause of these cliffs.
There is a lot of trash here left mainly by the fisherman and it is hurting the wildlife so if you see trash please pick it up and throw it away. The Hawaiian beaches are used by the native Hawaiian Monk Seals and hatchling Hawksbill turtles, both endangered species. Organizations are in the process of the clean up and are funded by the Hawaiian Wildlife Fund and NOAA. The location of the South Point Complex is in a public area and is open 24/7, but I recommend you come during the daytime so you can see the cliffs.