Great Blue slot

What kind of game the Great Blue slot is

Great Blue is an underwater-themed video slot from Playtech, the Isle of Man-based supplier better known for its Age of the Gods jackpot games. It came out in 2013 and has stayed in many UK casino lobbies since, partly because its single bonus is easy to understand and capable of large swings.

The grid has five reels and three rows with 25 fixed lines. Symbols include sea creatures such as turtles, sharks and seahorses alongside card ranks, which makes it one of the better-known animal slot machines. The whale is the wild and a shell is the scatter.

Playtech's own corporate website (opens in a new tab) describes the company as a gambling technology and games supplier; its games reach UK players through licensed casino operators rather than directly.

How the Great Blue slot machine decides each spin

As with every regulated online slot, the outcome is chosen by a random number generator on the game server the instant you press spin. The reels then animate towards a result that is already fixed. Here is the sequence for one spin.

1. Set your total stake. With 25 fixed lines, the stake is shared across all of them.
2. Press spin. The server draws a random number for each reel and maps it to a stop on the reel strip.
3. Fifteen symbols appear. The game then tests all 25 lines, paying any that run three or more of a kind from reel 1.
4. Whale wilds on a line stand in for missing symbols, and the paytable sets the value of each completed line.
5. Shell scatters are counted anywhere on screen; scatter wins are added and three or more start the bonus.
6. Your balance and session net position update before the next spin is allowed.

Because the result is decided at the start, nothing you do during the animation affects it. Our guide to how slot machines work explains the same process in more depth, including reel strips and weighting.

Great Blue symbols, wild and scatter

A doubling wild is a simple form of wild multiplier: a line of four turtles plus one whale would pay twice the four-turtle value. The rule is common in older Playtech games, but check the version you load, as paytables can be updated.

Great Blue free spins and the shell pick bonus

Three or more shell scatters start the bonus. The paytable describes a starting allocation of 8 free spins with a 2x multiplier, after which you choose 2 of 5 shells. Each shell hides either extra spins or a bigger multiplier, so the picks decide the shape of the round before the first free spin is played. The paytable puts the most generous outcome at 33 free spins with a 15x multiplier, and the round can be retriggered.

That makes it a pick-me bonus bolted onto ordinary free spins. The picking looks like a choice, but the values behind the shells come from the game's maths; you cannot pick 'better' by reading patterns.

Worked example: two very different rounds

The same £2 of line wins pays £4 or £30 depending on the multiplier. That spread is why the game is rated high volatility. The example holds the line wins constant to show the effect of the picks; real rounds vary in both.

Great Blue RTP and cost per 100 spins

Great Blue publishes an RTP of 96.03%, which is close to the norm for modern online slots. The house edge is therefore 3.97%. That figure is the long-run cost; your result in any session can be much better or much worse.

At 20p a spin and the UK minimum of 2.5 seconds per spin, 100 spins take at least about four minutes, so the average cost of a session depends on speed as well as stake. Our page on how long £100 lasts on slots works through that question.

Great Blue max win and UK stake limits

We could not verify a single maximum win figure for Great Blue from the developer, so we do not state one. The help screen lists the top line award and any cap on a round, and that is the number to rely on.

What UK rules do fix is the stake. Adults aged 25 and over can stake up to £5 a spin on online slots and 18–24 year olds up to £2, as set out in the Gambling Commission's online slots stake limit guidance (opens in a new tab). Every win scales with the stake, so a hypothetical 500x win would be:

Read more about how studios set top prizes on our max win caps page.

Is the Great Blue slot worth playing?

It suits adults who enjoy a classic five-reel layout and are comfortable with uneven results. People who want steadier returns could look at medium volatility slot machines instead.

Slots similar to Great Blue

Several games share the 25-line, five-by-three frame. Wolf Gold from Pragmatic Play is a better-known example with a money respin feature, and Yggdrasil's Vikings Go Wild uses 25 lines on a five-by-four grid. From Playtech itself, Age of the Gods adds a progressive jackpot.

Great Blue myths that do not hold up

• Choosing the same shells each time helps. The values are drawn at random every time; there is no fixed 'best' shell.
• A run of near-miss scatters means the bonus is close. Two shells and a third just off-screen is a losing outcome dressed up; read why near misses mean nothing.
• The game pays more at night. Time of day makes no difference online; see the best time to play slot machines.
• Higher stakes improve the RTP. The 96.03% applies at every stake in the UK version.

UK rules on the Great Blue slot

In Great Britain the game runs under rules introduced on 31 October 2021: no autoplay, at least 2.5 seconds per spin, no turbo or quick-stop, and no celebration of returns equal to or below your stake. The Commission explained the reasoning in its response to the online games design consultation (opens in a new tab).

UK versions are also supplied without a bonus buy, demo play is only allowed after age verification, and credit cards cannot be used to deposit. Winnings are tax-free for players. See our overview of UK slot machine rules for every current limit.

Where to play Great Blue in the UK

Playtech titles are carried by many UK-licensed casinos, but lobbies change and we do not claim that any partner below lists Great Blue. Search the game list at the site first.

Each deal below is restricted to newcomers aged 18+, and terms apply. At Coral, depositing and betting £10 on slots earns 100 free spins worth 10p each on selected games, with no wagering on winnings and 7 days to use them. PlayOJO gives 80 no-wagering spins on Big Bass Bonanza at 10p each for a first deposit of £10 or more (not available in Northern Ireland). Ladbrokes pays out 50 spins a day for 10 days after £10 of slots play. Coral and Ladbrokes share an owner, so check whether both accounts are allowed.

Set a deposit limit before you play and stop when it is reached. If you are worried about your gambling, the NHS gambling addiction page (opens in a new tab) explains how to refer yourself to a specialist clinic, and the National Gambling Helpline is on 0808 8020 133.

18+. Gambling should be entertainment that costs money, not a way to make it. Decide a budget before you play: plan a slot budget. Free, confidential help: National Gambling Helpline 0808 8020 133.