The submarine is a watercraft, and is capable of carrying up to 150 people. Its like a plane, just that it travels underwater. Going more than 1,300 meters, the submarine travels in a speed of about 60 km/h. Invented in 1864, the submarine is used until today and is very useful in wars and other situations.
Picture taken from here.
My grandfather already went in a submarine and told me it is a memorable experience. I'd like to travel in a submarine because it is totally submerged and maybe there are extraordinary views and animals that we are able to see. Also, it is an experience that not many people in the world have the opportunity to go through. The only fear I have is that if water enters the submarine somehow, and there is no way to take the water out, it will sink down if the crew takes too long to solve the issue and in a place so deep, there is no way I'd survive.