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Undine's Deep Slot - Review, Free & Demo Play

Undine's Deep
Undine's Deep
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Updated: 22.07.2025
Reviewed by: Joe Booth

In the mysterious fathoms below the beautiful mermaid is waiting for you in the lovely Undine's Deep slot! Released on 14/10/2014 this is a relatively old game, but it still holds up really well, not only compared to other Endorphina slots but period. And in addition to the fantastic design of the underwater world, in Undine's Deep, you can also win a great prize worth 9,000x your stake and play with different game modes, such as Gamble, Bonus Pop and Free spins.

There are a lot of other positive sides to this aquatic slot as well, and we are going to look at all of them in this Undine's Deep review!

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In this review
  1. Slot details
  2. Theme
  3. Bonus Rounds & Free Sipns
  4. Summary
  5. Where to play
General information about Undine's Deep slot

General information about Undine's Deep slot

Rating by Joe Booth:
7.4
Endorphina
Write a review +25 SJ points
  • Release Date:
    14.10.2014
  • Volatility:
    Medium
  • RTP:
    96.1%
  • Multiplier:
    Yes
  • Max. win:
    9,000x
  • Bonus game:
    No
  • Free spins:
    Yes
  • Scatter Symbol:
    Yes
  • Wild symbol:
    Yes
  • Symbol Stacked:
    No
  • Jackpot Game:
    No
  • Slot lines:
    10
  • Slot reels:
    5
  • Layout:
    5-3
  • Stakes range (€/£/$):
    0.1 to 100
  • Slot Theme:
    Marine, mythology
  • Technology:
    HTML5
More infoLess info

Licensed and tested by

  • GLI (Gaming Labs Certified)
  • ISO 27001
  • MGA
  • ONJN
  • Spel inspectionen

How to Play

We have created a set of simple instructions on how to play 5x3 Undine's Deep slot with 10 paylines:

  1. When downloading Undine's Deep, look for the three lines to the left of the reels to reveal your options

  2. To get started, click on the paytable option to find detailed information about the game, including the paytable, paylines, and bonus features

  3. If you are satisfied with the game's rules, return to the menu and select the bet option to place your bet. Undine's Deep allows you to wager between €0.01 and €100 on a single spin

  4. If you want to set up auto spins, you can choose how many spins you want and any limits under the auto spin heading in the menu

  5. On the menu screen, you will also find the option to check your stats, change your sound settings, change the language, or turn on the left-handed mode. When you're happy with your settings, press the X on the right side of the screen to exit

  6. When you're ready to start spinning, look for the transparent spin button on the right side of the reels. Click once to start a manual spin, or drag the button to the center of the screen to activate preset auto spins

Good luck!

Undine's Deep RTP and Volatility

7.2 
Undine's Deep online slot offers an RTP of 96.07% and a medium level of volatility.

In Undine's Deep, you will be playing with an average rate of both the volatility and the Return to Player. The volatility here is at a medium, thus Undine's Deep would be a good slot for all players, as it provides equality between the size of the reward you get, and how often you win in a spin. This is the most desired volatility level. Other than that, Undine's Deep has a great RTP, and after the win, you will be paid 96.07% of the win.

Theme

7.5 

For a slot machine based on the story of a water nymph, Undine's Deep action makes sense in the depths of the sea. This simple slot lets you see sunlight streaming through the water and seaweed growing on the sides of the transparent reels.

The soundtrack is dark and filled with suspense, which is the perfect complement to the storyline of a water nymph that could lose her life.

The symbols in this slot include a variety of sea creatures such as starfish and jellyfish to help you on your quest. The top prizes available in Undine's Deep are triggered when you line up five identical symbols along a payline. Using a wild substitute can double your winnings, and you can get a 3x multiplier in the bonus game.

Theme
Undine's Deep Slot - Paytable

Mobile Compatibility

Mobile Compatibility
Wish to enjoy this sea-themed slot from your mobile platform? You can! Courtesy of the modern and good HTML5 technology, Undine's Deep is available on all devices, and you will be able to play it via browser, provided that said device is connected to the internet. Thus, you don't have to download an app for Undine's Deep, and the gameplay will be no different than the one on PC.

About Endorphina

Endorphina develops slot games for online casinos. Thanks to deep market analysis and a carefully calculated mathematical model, the gaming content created by Endorphina fully meets the expectations of end-users — online casino players.

The games are a mixture of purely online slots and those that resemble games from land-based casinos. Thus, the interests of all segments of players, from beginners to high rollers, are taken into account.

Bonus Rounds & Free Spins

6.8 

Free Spins

The main bonus feature in Undine's Deep is the free spins bonus round, which is triggered by landing three or more scatters in any position.

In this round, every win will be awarded a 3x multiplier. You will be awarded 15 free spins with the option to trigger another 15 with three or more scatters.

Gambling Feature

After each win you have an option to gamble your win in a classical way by choosing a card that should have higher value than the Dealer’s, if you continue to win you have 10 attempts in total. But be aware that the RTP rate during this feature will be 84% only.
Undine's Deep Slot - Gamble Feature

Bonus Pop

If you want to get on to the Free Spins feature right away, you can buy 15 free spins with the help of the Bonus Pop feature. It will cost you 102x of your stake.

Undine's Deep Demo Play

Feel free to take a look and play the demo of Undine's Deep, because this mode is fantastic. In it, you can play the free version of this video slot, and it will have exactly the same bonus games and general gameplay as the casino version of Undine's Deep.

Max Win

8 
The max win on Undine's Deep is 9,000x your stake.

The Wild will also pay out on payline matches with top prizes of 9,000x, which is very high in the online slots market. You can also line up five scatters along a payline to win prizes up to 500x.

Also, note that the game does not have a progressive jackpot, but Undine's Deep does allow you to buy free spins which no doubt would be helpful to you.

Overall Rating

7.4

Undine's Deep online slot is an exciting nautical-themed game. Free spins, bonuses, and the chance to win up to 9,000x your bet are waiting for you.

The game also offers players medium volatility and RTP. Undine's Deep is for those players who love free spins and substantial max wins.

Hits
Free spins
Gamble Feature
Good max win
Misses
No Bonus Buy
No progressive jackpot

Undine's Deep Slot - FAQ

What is the maximum win in Undine's Deep Online Slot?

The max win on Undine's Deep is 9,000x your stake.

Does Undine's Deep slot support the mobile version?

Yes, you can play Undine's Deep right in your mobile browser.

What is the level of volatility and RTP in Undine's Deep?

Undine's Deep online slot offers an RTP of 96.07% and a medium level of volatility.

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Joe Booth
Joe Booth
Expert in: News, Blog, Slot reviews, Payments
Joe is an expert online casino player, who knows all the tricks and tips on how to get to the most massive wins. He is also an experienced online casino games reviewer, with hundreds of written articles behind him, on all kinds of online casino games. He makes sure to play them, see how they work, and then gives his honest expert opinion about them to other players, our readers. 

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