I've sewn 3 of these beach robes so far (one of them didn't get photographed, apparently). The hardest part is cutting the thick towels that I made the mistake of purchasing :-P
The stripey one above is for Erin, the others have been gifts for other toddlers.
This is the pattern. After making Erin's, I felt like the hood was a bit too shallow, so I added about an inch to the top of the hood piece and tapered it down to meet the lower part--this mod made it just right. And the sleeves seemed a bit long, so I shortened them on the blue one by about 1 inch. Still long enough to cuff, but not too long, hopefully.
I purchased the white bias tape for Erin's robe, but made my own bias tape for the other two robes. I love the look of the bias tape I made (and it is cheaper), but making the bias tape added a few hours to what would otherwise be a super quick project. For future robes, I may lean more toward pre-made bias tape. I used 1/3 yard cut of fabric for my bias tape, and this made more than enough. Might be possible to use a fat quarter, though not sure I'd want to risk running short.