Great Blue slot review

The Great Blue slot in a nutshell

Great Blue comes from Playtech, the gambling technology group founded in Tartu, Estonia, in 1999, now based in Douglas on the Isle of Man and listed on the London Stock Exchange. Released in 2013, it's a straightforward line game set under the sea, built around one wild, one scatter and a free spins round with a choice in it. You'll find Playtech's corporate background on the Playtech website (opens in a new tab).

How the features work in Great Blue

The feature set is compact, and the Racing Post's Great Blue guide (opens in a new tab) describes it the same way.

The whale wild

The whale is the wild. It substitutes for every symbol except the scatter, so it can complete line wins but can't help trigger the bonus. Any win it helps to form is doubled, which makes it the most valuable symbol to see in the middle of a line.

Pearl clam scatters and the free spins

Three or more pearl clam scatters, anywhere on the reels, start the free spins. You begin with eight spins at a 2x multiplier, so every win in the round is at least doubled.

The shell pick

Before the spins play, a set of shells appears and you choose two. Each one either adds extra spins or raises the multiplier above 2x. What each shell holds isn't shown until you pick it, and the possible prizes are listed in the paytable, so check the help screen if you want the full range. Landing scatters again during the round retriggers it for 15 more spins at the same multiplier you're already playing with.

Feature buy-ins aren't offered to British players following a Gambling Commission warning in January 2020. The free spins come only from landing three or more scatters.

Great Blue free spins: why spins and multiplier both matter

The shell pick feels like a decision, but the prizes are hidden until you choose, so there's no skill in which shell you take. What's useful is understanding why both kinds of prize matter. If the average line win per spin stays about the same, the value of a round is roughly the number of spins multiplied by the multiplier. The figures below are invented to show that arithmetic; they aren't the game's real shell prizes.

Multiplier boosts tend to swing the result more, because they scale every win in the round, including the rare big one. A 15-spin retrigger at a high multiplier is where Great Blue's bigger results come from, and it's the main reason the game is rated high volatility. Our guide to slot multipliers and the free spins feature cover these ideas in more depth.

Great Blue RTP and what it costs to play

With a 96.03% RTP, the house keeps 3.97% of stakes over the long run. A different way to picture that is to ask how much you'd need to stake before the expected loss reaches a set amount. For an average loss of £5, it's about £126 of total stakes (5 divided by 0.0397).

On a straight £20 at any of these stakes, the expected loss is about 79p. But a high-volatility game rarely tracks its average in a short session: you might lose the full £20 in 20 spins at £1, or catch a strong free spins round and finish ahead. Our explainer on variance and standard deviation shows why sessions spread so widely, and our house edge calculator runs the sums for your own stakes.

Great Blue max win and top prizes

Our checked data doesn't include a verified maximum win for Great Blue, so we don't quote one. The paytable inside the game lists the top line prizes, and the help screen states any overall cap. Either way, the 96.03% RTP already includes every big result, so a large top prize doesn't change the long-run cost. Our answer on what a slot's max win means explains how to read these figures.

Remember that a doubled wild win and multiplied free spins wins all count towards the published RTP. They're part of the average, not extra value on top.

How to play Great Blue online

1. Open the help screen and check the RTP. It should show 96.03%.
2. Look at the paytable for line values and the possible shell prizes.
3. Choose your total stake across the 25 paylines, within the UK limit of £5 a spin (25 and over) or £2 (18 to 24).
4. Spin, pressing the button each time; UK slots don't allow autoplay.
5. If three or more pearl clams land, pick two shells to set your extra spins or multiplier, then play the round.
6. Track the session time and net spend shown on screen, and stop when you reach your limit.

Great Blue under UK slot rules

Great Blue was released years before the current UK design rules, but UK versions must meet them all. The Commission's stake limit guidance (opens in a new tab) caps each spin at £5 for players aged 25 and over (from 9 April 2025) and £2 for those aged 18 to 24 (from 21 May 2025). Our slot stake limits page explains how the caps work.

• Autoplay has been banned on UK slots since 31 October 2021; our autoplay ban page has the detail.
• Each spin must take at least 2.5 seconds, with no turbo or slam-stop.
• Returns equal to or less than your stake can't be celebrated as wins.
• Net spend and time played are shown during play.
• Age and identity are checked before you deposit or use the demo.

Slots similar to Great Blue

More sea creatures and wildlife are on our animal slots page, and every game we cover is listed on the slots hub.

Who the Great Blue slot suits

Great Blue suits players who like a classic line slot with one meaningful bonus. If you'd rather have steadier returns, our low volatility slots page is a better fit.

Where to play Great Blue in the UK

Our partner offers below are for slots, but none names Great Blue, so check the casino's game lobby first. 18+ and terms apply.

• PlayOJO gives 80 free spins on Big Bass Bonanza, worth 10p each, to new UK customers (excluding Northern Ireland) on a first deposit of £10 or more. No wagering applies and winnings are paid in cash; the offer can't be used with other promotions.
• Coral gives new players 100 free spins at 10p each on selected games after they deposit and bet £10 or more on slots. Accept within 48 hours and play within 7 days; no wagering on winnings. Available from 1 October 2026 to 1 February 2027.
• Ladbrokes gives new customers 50 free spins a day for their first 10 days, up to 500 at 10p each on selected games, after depositing and spending £10 or more on slots. Claim by 23:59 each day; spins expire after 7 days and have no wagering.

Neither Coral nor Ladbrokes counts deposits made by PayPal, Paysafe, Neteller, Skrill or prepaid card. Both are operated by LC International Limited, so you may be able to take only one of the two offers.

18+. Every casino game has a built-in house edge, so over time you should expect to lose what you stake. Set a budget before you play and stop when it’s gone: safer gambling tools and support. Free, confidential help: National Gambling Helpline 0808 8020 133.