Amazon has popularized waterproof ereaders, but they are far from the first company to release one. Over the past 4 years quite a few ereaders have been released by a bunch of companies.
The first official release of a waterproof ereader came from Pocketbook, followed by Kobo, Barnes & Noble, and finally Amazon last October.
Here's a list of ereaders that are currently available in various markets around the world.
Amazon's flagship ereader, the Kindle Oasis 2, is the first Kindle to have a 7" screen and it is also the first Kindle to be released with waterproofing. It has an IPx8 rating, meaning it is certified for up to 60 minutes immersion in up to 2 meters of water.
Netronix makes several waterproof ereaders, including a couple models for Kobo and the previous Nook model.
Kobo also carries a couple waterproof ereaders made by Netronix. The Kobo Aura One features a 7.8" screen. It has waterproof guts that give it an IPx8 rating, meaning it is certified for up to 60 minutes immersion in up to 2 meters of water.
The Kobo Aura H2O 2 has a smaller 6.8" screen and the same IPx8 rating as the Aura One. Kobo also used to sell the Aura H2O. It had a waterproof shell, but is no longer available.
Watefi is a company that sells waterproofed electronics. They crack open the device, seal the electronics, and then close up the shell, taking such care that you wouldn't even notice it had been opened - until you dunk the gadget in water.
Waterfi sells a waterproof Kindle Paperwhite for $199. It comes with a 1 year warranty and has an IPX8 rating.
The Pocketbook Aqua 2 is the second waterproof model from this Ukrainian ereader maker. It has an IP57 rating and can handle being submerged in up to 1 meter of water for up to 30 minutes.
Tolino has 2 waterproof ereaders, including the 7.8" Epic and the 6" Vision 4HD. Both devices have waterproof guts covered in HZO, giving them protection for 30 minutes of immersion at a depth of 1 meter.
This Chinese ereader maker is selling at least one waterproof ereader, the Robinson Crusoe. It has a 6" E-ink screen, and its internal components have been sealed with a coating of HZO.
The Robinson Crusoe is only available in Russia.