Q. Are water toys like tubes, floats and inflatable mattress that are outside the water muktze on Shabbos?
Since their primary use is for swimming inside the water, which is not allowed on Shabbos can you use them when needed outside the water for seating or reclining on them??
A. Horav Shlomo Miller’s Shlita opinion is that if they are toys they are not muktze. However, utensils that most of their use is for swimming or in the water, they would be considered a Keli Shemelachto Leissur, or forbidden to use because of their prohibited use during Shabbos. However, they would still be permitted if one needs them for leaning or seating on them and even playing with them, as this is considered Letzorech Gufom. They may also be moved if one needs the space they are in.
If they are equally used in and outside the water, the Rov maintains that one can be lenient, since most probably any use of them would likely involve the Letzorech Gufom condition.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a