I have two friends (and divers) who use the Diva cup. They both like it and I have ordered one. I have been told there is a learning curve using them but was also told that they are no more messy than tampons.
Here is some info from an e-mail between us (no discussion of pros/cons of diving with one):
Apparently there is a rubber version (the original "Keeper") and the Diva Cup...the rubber version is a little stiffer, making it easier to insert but can be uncomfortable and if there is any concern about allergies to rubber, you might want to try the other. The rubber Keeper is also a little more expensive ($37 including shipping): (
http://www.thekeeperinc.com/)
The Diva Cup used to be cheaper on the "canadian" site but they have closed that loophole offering a US price as well as a Canadian price ($28.45 with shipping). It is silicone and does not have a long stem like the Keeper and Mooncup (but those can be trimmed): (
http://www.keeper.com/ or
http://www.divacup.com/)
There is also a British site with the same thing:
http://www.mooncup.co.uk/ (18.99 british pounds / currently $34.64)
The DivaCup and Mooncup are made from medical grade silicone and can be boiled to sterilize them. The Keeper is made from natural gum rubber and should not be boiled or put in contact with any kind of oil. The shape of the DivaCup differs slightly from the shape of the Mooncup and Keeper. The Diva Cup has a one year guarantee and the Mooncup and Keeper have a three month guarantee.
I was surprised by this link:
http://encyclopedia.thefreedictionary.com/Keeper which gave a really good decription of the device, pros and cons, etc.
Here is one person's experience:
http://pewari.may.be/archives/000187.html
Another experience with side by side pictures of Keeper and Diva Cup and discussion of shape of Moon Cup:
http://www.livejournal.com/community/the_keeper/33356.html
Another site with pictures/information:
http://www.mum.org/MenCups.htm