Different obscured or patterned glasses will provide differing levels obscurity. Your best bet is to visit a local glass dealer and ask to see several different patterns and look through them at objects from various distances. You'll quickly be able to pick out a pattern that provides maximum obscurity.

Keep in mind, however, that some acid washed or sand-blasted glass will become somewhat clearer when it's wet, so if you're looking at that type of glass, you might also ask to see the glass wet. You'll also need to choose a glass that can be tempered as a safety glass. Ordinary glass is not permitted in showers or doors, or within a certain distance of a door.

Have you considered white glass? It would be totally opaque as far as anyone seeing through it, but would still allow light to pass through.

Thanks, wa8b. I googled white glass but didn't find anything specific to opaque/light transmitting glass. Could you please provide a link to a manufacturer, distributor or retailer? It sounds promising. Allowing light transmission but not showing and shadows would be exactly what I'm looking for. I would even be a little creeped out if someone could see even a slight silhouette of my body throw a heavily frosted glass. And since the glass is facing a public street, it's imperative that this can't occur. Everyone I talked to said it would be very neat, however, if I could get this to work. I hear you on how water on frosted/obscure glass can reduce its opacity. Even if the "roughed" side of the glass is facing outside, the showerer could put on a show for the neighbors if the glass received some wind-driven rain. Thanks again.

Look at laminated glass with an high opacity interlayer. My new bathroom window is made from that instead of frosted glass.
Keep the lighting in the bathroom close to the glass so that it is between the occupant and the glass.

Cosmopolitan Glass makes an architectural tempered glass in various colors (including white) called "SpectroLam". There are probabaly other manufacturers making similar products. If you check with a glass fabricator in your local area, they'll likely handle the SpectroLam product, or something similar.

Here is a link that might be useful: Cosmopolitan Glass

How are you going to keep the window framing etc. from being spoiled by the water?

Maybe a conventional glass and obscure shower curtain would be a better solution.

Another thought, as Pharaoh mentioned, the location of the light, how about two pieces of glass with LED lighting in between. There are also waterproof LED to work with. Lots of ways you can do this!

Thanks for the tips. I just emailed Spectrolab and will report back with my findings. It looks like the application will consist of a laminated sheet of glass with a high-opacity plastic film between the two sheets.

Throwing light between the shower occupant and the glass is definitely better than behind the occupant because this will cast a shadow and increase the chance of a defined silhouette visible from outside. I do plan on putting two recessed 6" can lights inside the shower. In addition, I will have one low-power dimmable LED up-light on the roof eave (exterior) directly behind the glass. This will create a unique lighting effect for the frosted glass shower wall when the shower isn't in use (imagine a glowing wall from inside the bathroom). Basically, I can have a cool exterior lighting effect combined with an even cooler interior lighting effect with this setup. I hope it all works out.

Oruboris - Why would the window frame be spoiled by the water? From the interior, the tile will be laid up to and on top of the glass. From the exterior, this would be a traditional glass in standard aluminum window frame set up. Maybe I'm missing something?

Sounds interesting, hope you will show some how to pics as you work!

Around here, we'd worry about condensation. Since you are in Hawaii, I guess the temperature difference wouldn't be significant.

It doesn't sound like you are ever going to be able to clean or open that window once the inner glass is on-- don't know if that would be an issue for you.

I'd just check with a local tile man to see if they have done this, or know of why it shouldn't be done...

Thanks for your help guys. I decided on a four-panel frosted glass system with the top panel being operable as an awning. This way the window can be cracked for ventilation and people outside still can't see in.

The lighting effect from the exterior is a bit more complicated now because of the 3 aluminum mullion "bars" (the window frames are clear anodized alum) that will run horizontally. I'll have to see if I can mount 4 individual spot lights on the edge of the exterior eave (at the base of the window) and point each light at one glass pane. This way the window will glow when looking at the window from the interior.

This is a lot of work to create this one effect. I'm definitely not normal.

If anyone has any advice as to choice of glass (or film that can be applied to a standard window), please let me know. I am currently having the window manufacturer (which hasn't been chosen yet but leaning towards Fleetwood) spec a frosted version but I'm afraid it won't be sufficient to create the privacy I desire.

I discovered that the glass companies blew off my concerns about my silhouette being visible. I finally figured out on my own that in addition to 2 panes of frosted glass I added two smaller recessed lights the pointed to tue window. At night, i would make sure the lights were on. From the outside a person could only see bright light, no silhouette.