Corrected sentence:
The deep blue sea hides amazing animals: huge blue whales, fast sharks with sharp teeth, and anglerfish with glowing lures. The deeper you go, the stranger everything gets.
Why this is correct (in simple words):
- The colon (:) is okay because it introduces the list of animals.
- We use commas to separate the items in the list. The comma before "and" is fine here.
- Words like "huge" and "fast" are just small word choices — the original words "big" and "quick" were also correct.
- The second sentence is correct and tells us what happens when you go deeper under the water.
Short tip: Your original sentence was already good! I only changed a couple of words to make it sound a bit stronger, but you can keep your own words if you like them better.