Disclosure: I received this at heavily discount in exchange for my honest opinion.
This suit is called the Newland Girl's 3pcs Mermaid Sea-Maid Tankini Mermaid Swimwear Bikini at 12.99 is definitely one of those Amazon only kinda finds. So I ordered this bathing suit for my 6 almost 7 year old Lily, she is as most girls her age a mermaid fan so I thought she'd love it. When I thought Lily would love the suit I most definitely was not wrong, she was so excited to get to wear a tail. The material is a thin stretchy material so it has some give and the top is definitely an area that you can get more give if you have a "fluffier" little mermaid. I got the XXL which I actually don't like in the naming, I wish they would have just stuck to age ranges rather than sizes but that is all personal preference, but it fit her very well. The length was perfect a smig too long but she is on the shorter size of 6 and it will last all through what I expect will be a growth summer. The end of the tail has an opening that allows her to walk comfortably similar if you wear a mermaid style dress or skirt, but with the extra stretch in the fabric makes it even more comfortable.
This however is not a tankini at least with the implication that it's designed to cover part of the mid-drift, it's more of a halter top bikini. I love the color the fabric is super vibrant and reflective looking like scales. It's definitely a little girls dream bathing suit.