With a larger screen and waterproof design, Amazon's new Kindle Oasis is for well-heeled readers who struggle to put down a good book.

Starting at $389, the Oasis has dropped in price but is still the most expensive Kindle by far. In return it steps up to an 18cm screen – with the extra space letting you see more text, or else bump up the font size. Despite this, it's barely larger or heavier than the others in the stable.

It's beautifully balanced and comfortable to hold for hours, while the screen looks fantastic and is easy on the eyes.

Onboard storage is also bumped up to 8GB or 32GB, although you'd only need the latter if you're a fan of Audible audio books, which take up about 150MB each. There's no speaker or headphone jack. Instead, the manufacturer has added Bluetooth for connecting an external speaker or wireless headphones. This means you can leave your expensive Kindle in your bag when listening to audio books on the train.

The e-Ink monochrome display ensures the battery lasts for weeks, only using power when you turn the page by pressing the buttons or tapping the screen. Thankfully the touchscreen still responds when it's wet, and this Kindle can survive submerged in two metres of water for an hour, so it's fine for reading at the beach, by the pool or even in the bath.

Like the $179 Kindle Paperwhite and $299 Kindle Voyage, there's a backlight for reading after dark. Naturally this takes its toll on the battery, as does Bluetooth as well as enabling Wi-Fi for connecting to Amazon's e-book store. Even pushed to the limit, the Oasis' battery is good for days, with new fast-charging technology allowing a full recharge in two hours.

All up, the new Oasis is an impressive upgrade, but only if you're convinced you'd appreciate the benefits over the cheaper Paperwhite once you're engrossed in a good book.