Sea of Thieves' Season 4 trailer shows off deep sea Siren Shrines, Treasuries, and more

Following last week's Sea of Thieves Season 4 teaser, Rare has provided a more substantial run-down of features pirates will be able to plunge into starting this Thursday, 23rd September.

Sea of Thieves' fourth season is all about expansion, but rather than out - as was the case when the Devil's Shroud parted to grant access to the fiery Devil's Roar back in 2018 - we're going down, with new areas of the Sirens' vast underwater kingdom opening up all over the map, including six new Siren Shrines and a number of Siren Treasuries.

The former, as presented in the Season 4 trailer at least, appear to be more substantial dungeon-style activities, each promising "unique challenges and threats", as well as plunder for those able to solve their mysteries.

Siren Treasuries, meanwhile, are wave-based challenges that sound a lot like Skeleton Fort events, albeit underwater - rewarding lucrative new coral-encrusted treasure to those players that manage to fend off waves of Ocean Crawlers and Sirens.

There's also a third (although less clearly defined in the trailer) underwater activity unlocked by finding special new Coral Message in a Bottle quests that point to additional pockets of deep sea real estate, rewarding a new "rare and valuable" item known as the Breath of the Sea.

Quite a few questions remain - it's unclear, for instance, if these new areas can be visited at any time or if they're activated on a rotational basis like other World Events - but Rare has at least detailed a few of the handy mechanics it's introducing to facilitate underwater play.

Any treasure located beneath the waves can, for instance, be stored within special Sunken Merfolk Statues; crews can then reclaim all stored treasure from a friendly merperson once back on the surface - which should go someway to mitigating the fact that exploring these new underwater areas will leave ships conspicuously exposed while players battle it out below.

Elsewhere, a fresh batch of Commendations tied to the new underwater kingdom content are arriving as part of Season 4 and completing these will unlock new cosmetics, including the Sunken Sorrow ship set, scar, weapons, and the rather spooky Coral Curse.

Then, of course, there's a refreshed 100 levels of progression and associated rewards, with both a free tier and a premium tier available once more, the latter featuring some rather splendid Hallowe'en-themed ship cosmetics and costumes, all based around a cheerfully sinister pumpkin-headed fellow - who might perhaps play a more prominent role later in the season, should Rare have some spooky Hallowe'en celebrations planned.

You can see all this stuff in action - plus the new Pirate Emporium additions - in Sea of Thieves' Season 4 trailer above. Things kick off this Thursday, 23rd September, on PC and Xbox.