Who is this? Why is he swimming?

Once upon a time, there was a penguin named Pingu. He was a very curious penguin, and he loved to explore. One day, Pingu was swimming in the ocean when he saw something strange. It was a large, black object that was moving very fast. Pingu swam closer to get a better look, and he soon realized that it was a submarine.
Pingu had never seen a submarine before, and he was very excited. He swam up to the submarine and started to follow it. The submarine was going very fast, and Pingu had to swim as hard as he could to keep up.
After a while, the submarine stopped and Pingu swam up to it. He looked through the window and saw a group of people inside. They were all wearing strange uniforms, and they were all looking at him.
Pingu was a little bit scared, but he was also very curious. He swam closer to the window and waved at the people inside. The people inside waved back, and they all smiled.
Pingu stayed with the submarine for a while, and he watched as the people inside worked. He learned that the submarine was called the "Nautilus," and that it was exploring the ocean.
Pingu had a great time with the people on the submarine, and he learned a lot about the ocean. When it was time for Pingu to go, he said goodbye to the people on the submarine and swam back to shore.
Pingu told his friends all about his adventure, and they were all very impressed. They had never heard of a penguin who had been on a submarine before. Pingu was very proud of himself, and he knew that he would never forget his adventure.