Here’s a great winter / aquatic cardigan for your baby / child.
Knitted in double knitting yarn.
I choose a tuxedo style, with black back, sleeves and white front like a penguin.
You could knit the cardigan in sea blue with the black and white penguin motif.
The motif is worked over 14 stitches so you could adapt a hat to add the motif or add more penguins to front or back (this may require a bit of experience in pattern designing)