SCORKL is a small, portable and easy to refill oxygen container for your underwater experience. It gives you up to 10 minutes of underwater exploration. It has a scuba tank pump so you can refill it anytime you want to dive. Use it cautiously and with a lot of fun!
Terrible, dangerous idea as confirmed by top freedivers I've discussed this product with. Any kind of consumption of air at depth requires tables to avoid decompression. Training and supervision by a qualified scuba diving teacher is essential.