The only reason I'm giving it a 4 and not 5 star is that it's a little small for the seemingly intended purpose of being a swim bag. Now that might not be entirely fair because the specs do list the size, but due to the shape of this thing, it's not like the specs can be really spot on as it's not a simple rectangle. Still, this product works fine, and it's a nice choice for a little kid because it makes the backpack a little more fun.What we do with it is use it for our preschooler's swim class. It is adequate to fit a small towel, swim suit, goggles and perhaps another small item or two. This is tight when you fully seal it. But it works. Sometimes the kid does want to carry it on back and that looks really cute, but typically we're just slinging it over an arm to carry it along with other school items. It's great to keep the wet or damp swim class stuff well separated from everything else. It might not technically be wholly waterproof, but after a couple months of use now, we've never had anything that we put in there get anything else in contact with the bag wet.This backpack which is well made btw, is absolutely adorable. At first it seemed small as did another backpack Trunki we got (NEMO), but I was proven wrong. I started to stuff these two backpacks with items and I became more impressed as these adorable backpacks 'filled' out, holding nicely what I had placed in them! Actually I tried them on my own 5'1 back and it fit me & was comfy and heck....I think a fun loving adult could wear there no problem! In fact our DIL will sometimes wear it and our adventuring adult son asked for one for the fun of it....So imagine the glee of a little child getting these backpacks?! They are well made & hold enough for that age group to handle! I cannot rave enough --- I love when I find things for my grandkids that make me smile & them jump for joy!It's so cute my daughter got it for swim team. She uses a very thin light weight special towel that folds up very small, swim suit, goggles, and a swim cap it all fits but if she had to use a regular towel it wouldn't all fit. Okay it would probably all fit if I folded it and packed it for her every time but the way she just crams it all in no way.It’s just like a regular waterproof bag but has fins and a fish face. (And is a triangle shape) As a 24 year old kayaker that loves fish I had to have this bag. It’s a bit small (of course it’s for a child) fit me very snug but I ended up having extra straps so I just sewed extensions onto it and now it fits perfectly 10/10 would recommendWe own three of these handy bags, sacks, backpack, sorry Trunki and they have been everywhere and through everything with three boys. Hiking in Sierra Nevada mountains, cruising the beaches from San Diego to Leo Carrillo State Beach. My kids will not let me take them out of the house unless they can carry their own water bottles, change of clothes, towel, snorkel gear, you name it. They are large enough to fit a huge beach towel ours are roughly 5 feet long and a few feet wide plus any other essentials needed for your day trip. Price is great had one that suffered a small snag on a tree branch and ripped a very small section of the mesh pocket on the side of the bag but still useable. Many compliments from strangers cause they look cool and fit perfectly on a small child's back.This is the third one I bought. I bought two four years ago and made my children carry their own pool/swim stuff. One of them was the small fish. Now he’s all grown up and needed a bigger bag. The other two have held up really well. We also get lots of compliments while teaching responsibilityI’m 25 and I use this bag for hiking to carry a 1.5 liter reusable water bottle and for school to carry two small notebooks, a pencil case, a small water color set, and my keys and wallet. I thought some of my hikes would’ve killed it, but it kept up and is still keeping up a good fight.I haven’t really had to test its water resistance, so I can’t vouch for it, but for all those other things, it’s wonderful.Great backpack for my kindergartner! There's just enough room for his class binder and an extra pair of clothes. The mesh side pocket fits his small reusable water bottle- so far I haven't made use of the tiny zippered compartment located beneath the sharks tail...just big enough for a small pack of fruit snacks or chapstick. He loves his shark backpack, I know that it's typically marketed for going to the beach or poo(which is what he'll use it for after kindergarten), but it works just fine for his school needs and his fave: the dorsal fin and shark teeth at the top of the bag! *Also super lightweight, cleans/air dries (while hung outside) quickly and easy for him to open and close :)Compact swim bag. Fits my preschooler's swim suit, towel and goggles perfectly and they love carrying it to and from their lesson. Completely waterproof so it stops the water from the swimsuit from getting the car wet on the journey home but is easy to dry once empty. This is the second bag I have purchased. My other child has the blue version and has used it for four years and it still looks brand new!A great bag, holds the damp form the kit, the outside remains damp but not wet. It's sturdy for kids and cute!!! The top needs rolling to close, a zip would be an improvement to save faff of rolling, but we are really happy. WOuldn't suit a normal size towel but we fit our travel change mat, nappies, swimsuit and baby towel in ors happily.This is a great backpack. When it first arrived, I thought it was going to be too small but when you open it up it's clear that you can fit quite a lot in there - you could easily fit swimming stuff and a drink and snack. The straps are comfortable, the shape sits against the back very nicely and my sons seems to have no problem carrying it (he's 4.5 and pretty sturdy). The way you close the bag is quite interesting - the top folds over a couple of times and then the two ends clip together. I think children will get used to how this works with a bit of practise. The clasp itself isn't too stiff, which is great for little hands. I would definitely recommend this backpack: it's a very fun design, it packs down to nothing but expands to fit a fair amount, it has a useful little pocket for change, snacks, stones, whatever your little one likes to collect and it's not too expensive, especially considering they can probably start using it when they're very little. I will have to take look at the famous Trunki suitcase now, I'm impressed with the brand's design and holidays aren't far off.I love this little bag, though something about the design bugs me, I think is the way it closes at top isn't that secure when my boys run about and jump with stuff in. Otherwise, looks great, we use for swimming lessons each week, fits everything with a mircofibre towel. We also used on holiday everyday for beach and poolside and day trips, meant my 4 and 6 year old boys could carry there own stuff and it wasn't too heavy and they didn't complain. Wish they were a tad cheaper as find the brand a bit expensive personally.I bought one of these in red for my son last year as his old swimming bag had broken and I don't know why I delayed getting my daughter one. There really is no comparison between the design of these bags and the horrible PVC things you normally find on the high street. My daughter loves her new "Inky", and that she can comfortably put it on herself (emphasis there as her previous PVC bag was actually sharp around the edge and the Velcro on the string strap kept coming undone) with nice padded straps so she feels very independent. She likes the little pocket at the bottom for putting her hairband in. I like that it's such a waterproof yet lightweight material which is perfect for swimming so you don't have things hanging around drying for days afterwards! One happy family.