Undine's Deep
Undine's Deep Slot
Value 94
Gameplay 91
Art 94
Bonuses & Features 91


Undine's Deep is an ocean underwater themed slot game released and supplied by Endorphina. It features goldfish, jellyfish, starfish and even mermaids! Let's discover more details bout this interesting slot.


Undine's Deep is a 10 paylines, 5 reels slot from Endorphina. Creatures of the deep seas will appear on your screen, including mythical ones like the the seductive mermaid.

Before you play, make sure that the bet amount is set according to your requirements and preferences. First adjust the coin value (from 0.01 to 1) by the round coin symbol at the top/left corner. And the bet level afterwards (from 1 to 10). Autoplay feature is available, and you can activate it  clicking the button AUTO or by dragging the SPIN button to the left in case of the mobile version. But before that, it's sensible to adjust the auto play settings on the MENU.

You will notice the regular low valued symbols 9, 10, J, Q, A and K, as well several high valued ones. There is a wild symbol, that is the goldfish, it substitutes for all other symbols except the scatter. In addition, on a pay-line, it doubles the price of the normal win.

Bonuses & Special Features

The mermaid is the scatter symbol. You will need to land 3 or more in order to trigger the Free Spins feature. That feature is 15 Free Spins will all wins tripled. It's possible to retrigger the feature is you land 3 or more additional scatter symbols.

After any win you have the option to either take it or risk it for double the winnings. That is the normal Risk Game feature by Endorphina. We recommend to check after a big win. If the card shows is 2 then it's risk free, open any of the four and if its greater than the shows card then you win double.

Art Design

Undine's Deep has excellent visuals. With an underwater deep sea them, is very colourful game and all symbols fit its theme.

The soundrack and sound effects are well done, and induce a calming effect. Careful though, don't get carried away, if you win a moderate amount then quit the game and cash out!


The base game has potential if you hit the starfish or the sea urchin symbols on a line along with one or more wild (remember, wilds double the win). That will pay 150 times the bet amount. And it's doable, we hit it several times.

However, the real potential is with the Free Spins feature. According to our results the feature frequency is once in 253 spins in average. The average payout from the feature is 102 times the bet amount.

It's possible to retrigger the Free Spins feature and even land 5 scatters. We did that couple times. The payout of 5 scatters during the feature is an amazing 1500 times the bet amount.

Also remember, after a big win to check the risk game for. If the card is 2 then pick any of the 4 cards, without risk to lose.

Test Results

  • Average Free Spins Frequency: 253
  • Min Free Spins Payout: 15.5 x stake
  • Max Free Spins Payout: 1706 x stake
  • Average Free Spins Payout: 102 x stake
  • Shortest Period between Free Spins: 7
  • Longest period without Free Spins: 1173


  • If you are looking for a short section then play to a Free Spins feature and quit immediately afterwards.
  • In the above case it is better not to run for more than 300 spins, although a maximum limit of 200-220 is preferable.
  • The game can run without a Free Spins feature for more than 1000 spins, hence it will take away from your bankroll nearly 400 times your bet amount.
  • A long session comprises multiple Free Spins. Quit if your balance increases over 80 times the bet amount and it doesn’t give you feature in 240 spins.
  • In any case and if your balance increases over 100 times the bet amount you should leave the game and try again later.
  • After a massive win from the Free Spins feature (like 5 scatters), continue play for 120 spins. It gave us another feature often in the next 100-120 spins.
  • the suggested stake is your bankroll divided by 200 times. Example, if you play with 100 then bet 0.4 to 0.5 per spin.
  • Essential is to never play with money that you can't afford to lose.
  • After a successful session leave the game and cash out the money.


Undine's Deep is a well done slot game and we will recommend to everyone, but especially to experienced gamblers. You always have the option to play in demo mode (practice) and discover its mechanics and gameplay. We are urging you to do that if you are unsure about anything at all.

The game is a high volatile one and often you will have section without considerable wins. But the potential is there and we hope to hit something massive.


  • Excellent payout potential, especially during the Free Spins feature
  • Colorful visuals yet not distracting
  • Endorphina risk game (gamble feature)
  • Relaxing soundrack & sound effects


  • The high volatility is not suitable for the more casual players


Software Endorphina
Released 2014
Paylines 10
Reels 5
Min Bet €/£/$ 0.01
Max Bet €/£/$ 100
RTP 96%
Bonus Game No
Free Spins Yes
Multipliers 2x 3x
Wild Symbol Yes
Scatter Symbol Yes
Progressive No
Autoplay Yes
Variance High