long snorkel to replace cover on main drain?

[Vinyl_Guy]

A handy way to help yourself stay down is one of those plastic coated dumbells. It works just like a handle on the bottom. You could also use a milk jug full of sand or gravel.

If it's a vinyl pool I suggest one of your Winterization water bags. Even an old leaky one will work. You don't want to bring anything hard down with you that might get banged around. Many people have them on hand too.