ChacoBoy's Women's Sandal Child

Are these goid to wear when tubing in a river? Or at a waterpark? Do they dry quickly?

I wear a 10 in sketcher go-walks but a 9- 9 1/2 in other shoes. Should I get a 9 or 10? Maybe 9 wide?

If I wear an 8.5 in regular shoes, what size do I buy in these sandals? 8 or 9?

Are the soles supposed to be soft? I just got these delivered today and the soles are very hard.