Ocean and underwater slots

What ocean and underwater slots are

An ocean slot takes you under the surface. The reels are framed by coral, kelp or sunken hulls, and the symbols are sea life: sharks, whales, dolphins, turtles, octopuses, starfish and treasure chests. Some games add mythology, with Poseidon or the Kraken, and a few go further, into submarines and naval history.

Lobbies often put ocean games and fishing slots side by side, but they are different families. Fishing games are almost all built on one idea – fish with cash values and a fisherman who collects them – while underwater games use a much wider range of mechanics.

Ocean slots vs fishing slots: what is different

Ocean and underwater slots compared

Figures are the top or default versions published for each game. Where a max win isn't in our verified figures, the game's own help screen will show it.

The Novomatic classics: Dolphin's Pearl Deluxe and Lord of the Ocean

Two of the oldest sea games still in UK lobbies come from Novomatic, now published online through Greentube. Dolphin's Pearl Deluxe (2009) and Lord of the Ocean (2008) both use 5 reels, 3 rows and just 10 paylines, with RTPs of about 95.1% and high volatility.

Their features are simple. In Dolphin's Pearl Deluxe, the dolphin wild doubles the line wins it helps complete, and free spins pay multiplied wins. Lord of the Ocean uses the ‘book’ formula: before free spins start, one symbol is chosen to expand over whole reels whenever it lands, which is the same idea behind Book of Dead and Book of Ra Deluxe. With only 10 lines, the base game pays modestly and most of the value sits in that one feature.

Great Blue: the whale wild and the shell pick

Playtech's Great Blue (2013) is one of the most familiar underwater slots in the UK. It runs on 5 reels with 25 paylines, a 96.03% RTP and high volatility. The whale is the wild and boosts the wins it completes, and the free spins round starts with a pick: you open shells to add extra spins or raise the multiplier before the spins begin.

The pick feels like a choice, but the prizes behind the shells are decided by the game, so there is no right or wrong shell. What the pick does do is make the size of each free spins round vary a lot, which is one source of the game's high volatility.

Razor Shark and mystery stacks

Push Gaming's Razor Shark has the highest RTP on this page at 96.70%, on a 5×4 grid with 20 paylines and high volatility. Its signature is the mystery symbol: stacks of mystery tiles land and then all reveal the same symbol, so a reel can turn into a column of one high-paying sea creature in one go. Free spins add a multiplier that grows as the round goes on.

A high RTP doesn't make a game gentle. Razor Shark's return is concentrated in the reveals and the free spins, so long quiet stretches are normal.

Sea monsters and submarines: Release the Kraken and Das xBoot

Pragmatic Play's Release the Kraken uses 5 reels and 4 rows with 20 paylines, doubling to 40 in free spins, with a 96.50% default RTP, high volatility and a 10,000× cap. At 20p that cap is £2,000.

Das xBoot (Nolimit City, September 2021) is in a different category. Set aboard a wartime submarine, it uses an unusual 2-3-4-4-3-2 reel shape with 576 ways that can grow to 75,712, and it is rated extreme volatility with a 55,200× cap. Its RTP of 96.03% is ordinary; its distribution of wins isn't. Most sessions will return little, and a very small number will return a great deal. It suits only players who are comfortable losing a session budget most of the time.

Ocean slots RTP: what the gaps cost in pounds

The RTPs on this page span 1.63 percentage points, from 95.07% to 96.70%. Here is what that means over different amounts of play:

Over a single 100-spin session, volatility will swamp these differences. Over months of regular play, the RTP gap adds up, which is why the high RTP slots page is worth a look if you play often.

How to check an ocean slot before you play

1. Open the game's help screen and find the RTP line; compare it with the table above to spot a lower version.
2. Check the volatility rating and the max win as a multiple of your stake.
3. Read how free spins trigger and what happens in them – a pick, an expanding symbol or a growing multiplier.
4. Note whether wins come from lines, ways or clusters, as this changes how often small wins appear.
5. Pick a stake that gives at least 100 spins from your budget and set a deposit limit before your first real spin.

Ocean games with pirates, treasure and shipwrecks also turn up on our pirate slots page, and island games such as Aloha! Cluster Pays use cluster wins rather than lines.

Where to play ocean and underwater slots in the UK

Ocean games from the studios above are widely carried by UKGC-licensed sites; search the lobby by title and check the RTP version in the help screen. PlayOJO gives new UK customers (excluding Northern Ireland) 80 spins at 10p on Big Bass Bonanza with a first deposit of £10 or more, with winnings paid in cash and no wagering. Coral gives 100 spins at 10p on selected games after you deposit and bet £10 on slots; the spins must be accepted within 48 hours and used within 7 days, and spin winnings carry no wagering. 18+, terms apply.

18+. Gambling should be entertainment that costs money, not a way to make it. Set a deposit limit before you play: how to set limits. Free, confidential help: National Gambling Helpline 0808 8020 133.