They built a submarine From tuna cans and tape To do the deepest diving To see the oceanscape Down, down, down through wet unknown They sunk below like people stones Longing to see exotic creatures In a homemade sub with shoddy features At the bottom of a rocky fissure They learned an awful lot about pressure Three miles down where sub hit ground There was no time to look around For the ocean piled upon the ship Made metal bend and tape go rip A squishy end to a perilous trip A crew squeezed out as people drips They floated back up to the top A pressure pasted pile of glop Water pressure can be a beast Human bodies can't bear the least But tell your mother not to worry The sub I made is much more sturdy -B.C. Byron

Another science poem, and you can expect more. Water pushes from all sides and it pushes harder as a submarine, fish, or human diver goes deeper. I saw a science show once where they tested water pressure with an old fashioned, metal helmet diving suit. They filled the diving suit with meat and sent it down into the deep. As soon as the air hose was closed off, the pressure from inside the suit was less than the ocean pressure outside and GOOSH! The meat turned into liquid and squished up into the metal helmet. Yuck! Water pressure is a powerful force.
Another cool experiment I saw involved shooting a bullet into water (don’t ever do this). The water pushes back on the bullet so hard that it stops within a few inches of water. Bullets from higher powered guns had even less effect in the water. The bullets fell apart into tiny bits from the force of the water. Water is chock full of great physics lessons.
So how do fish stand all that pressure when a metal submarine can only go down so far without crushing? How can they survive even 4 miles down in a deep ocean trench with thousands of pounds of pressure on all sides, constantly? I leave that puzzle to you to ponder. Just try to solve it before you go to Google to get the answer.
Once in a while I like to slip in some real science in my poems, but there is always some good fun. Thanks for reading.