Umbrella for a pool sun shelf?

In our new pool, we've got a big first step -- call it a small-sized sun shelf that would accommodate one person -- and there's an umbrella sleeve at the side of the step near the coping. I'd like to get an umbrella for use in that sleeve -- something that's suitable for being placed inside a pool (read: no wood, no steel).

Is there a favorite place folks here turn to, to buy an umbrella for use inside the pool?

My only concern is that I'm tall -- over 6' -- and I don't want to get poked in the eye because the shade of the umbrella is too low as I step off the deck and into the sun shelf.

Thoughts or recommendations?