This is very easy. I did it right from my mind and it was an instant idea when I saw this scruffy leftover of lace and the shells I originally bought for an Little Mermaid-bikini bra :D
Get sticks & glue lace on them
Get shells and glue them on the fabric. I used cardboard as a pad.
You can also decorate it with other maritime stuff, I think ropes would be looking nice too :)