The 

Panama Canal

is a unique engineering construction of the 20th century. It is a navigable canal that connects the Gulf of Panama in the Pacific Ocean with the Caribbean Sea and the Atlantic Ocean, located on the Isthmus of Panama in the territory of Panama. Its length is 50 miles (81.6 km), including 40 miles (65.2 km) on land and 10 miles (16.4 km) along the bottom of the Panama and Limon Bay (for the passage of ships to deep water).
The construction of the Panama Canal was one of the largest and most complex construction projects implemented by mankind. The Panama Canal has had an inestimable influence on the development of navigation and the overall economy in the Western Hemisphere and throughout the world, which led to its extremely high geopolitical importance. The sea route from New York to San Francisco through the Panama Canal decreased from 139808 miles (225,000 km) to 59030 miles (95000 km), and it had greatly facilitated shipping throughout the Western Hemisphere.
Vessels of various types pass through the canal, including private yachts as large tankers and container ships. The maximum size of a vessel that can pass through the Panama Canal has become a de facto standard in the shipbuilding industry, under the name of Panamax.
The passage of ships through the Panama Canal is carried out by the pilot service of the Panama Canal. The average time of passage for a vessel through the canal is 9 hours, the minimum being 4 hours 10 minutes. Maximum capacity is 48 ships per day.

According to the Treaty of 1903, the United States was granted everlasting possession "of the land and the land area under water for the construction, maintenance, operation, establishment of hygiene and protection of the said canal," provided by Article 2 of the Treaty. Article 3 gave the US all rights as if they were sovereign territory. The United States also became the guarantor of the independence of the Republic of Panama and received the right to maintain order in the cities of Panama and Colon in the event that the Republic of Panama, according to the US, was unable to maintain order. In fact, the channel is completely under the control of the United States, who provides efficiency and safety.
As a part of the demonstration of marine satellite navigation system, I spent a whole day onboard the cruise liner Celebrity Infinity, during its passage through the Panama Canal.
In the early morning, the ship entered the canal from the Pacific Ocean and, at slow speed, headed toward the Atlantic Ocean.
Both oceans are known to be at the same level, but the ferry across the channel takes longer because most of the time is spent on passing through the locks.
First, the lock system lifts the ship to a height of 311 feet (95 meters) above sea level into the artificial lake, where the ship sails for a few tens of kilometers, and then another lock system lowers the ship back into the ocean.
The passage through the canal started with the 

Miraflores locks

.
In order to help a ship pass through the lock, thick mooring ropes are tied to all four sides of special locomotives running on rails on both sides of the lock, and these locomotives push the ship forward. For such a large ship as the Infiniti, the gap between the lock walls and the hull is sometimes less than 3 feet (1 meter) on each side.
Two bridges cross the canal. Only these bridges connect the northern and southern part of Panama.
In December 2010, the 

Panama Canal

was closed for the first time in 90 years due to continuing heavy rains and landslides. It has since been decided to abandon the gentle slopes of the hills and make them on the base of fortified terraces.
The canal is constantly expanded. Now, there are works held in many places in order to increase its capacity.
In some places, the water is very muddy because of constant earthwork operations. 
And this is the view of a lock from inside: the lock is closed and the water begins to flow into (or merge) through special intakes.
When a ship is lowered, the water flows out of the lock and goes into the lake in mad torrents.
And there were crocodiles resting on the banks of the canal, covered in grey dust.  
We passed the last lock and went into the Atlantic!
Soon we passed by the port of the city of Colon, on the Atlantic Coast of Panama.
Generally, it was interesting and exciting.