Why did it take so much time and effort to build the panama canal?

The canal is 48 miles long which meant there was a lot of digging, preparation  and sweat. It dramatically reduced the amount of time that ships had to sail from the Atlantic to the Pacific.

It was plagued by difficulties; rain, land sliding, escalating costs, fraud, inadequate machinery, and the dread plague of yellow fever and malaria doomed the project.

Drought resistance because they are close to a lot of supplys 

Which figures are you talking about?