Essex-based four-piece We Are The Ocean have never been ones to play by the rules. After all, after spending five years building a supremely committed fanbase, their last album – 2012's Maybe To-day, Maybe Tomorrow – dealt effortlessly with a change in line-up and emerged with a bold, beefed-up new sound. But that's got nothing on its imminent follow-up, Ark, which sees the one-time post-hardcore outfit heading ever further into the unknown. Most bands don't even get to make four albums these days and of those that do, most have no surprises left in their creative locker. You'll be pleased to hear that We Are The Ocean, are not most bands.

In the same way that Liam Cromby (vocals), Alfie Scully (guitar), Jack Spence (bass), and Tom Whittaker (drums) knew that Maybe Today, Maybe Tomorrow represented a "defining moment", so they realised Ark needed to give full rein to their restless musical ambitions.

Their last album Maybe Today, Maybe Tomorrow marked a fundamental shift in the way people saw We Are The Ocean, as they continued to go onto bigger and better things. The 10 tracks that comprise MTMT constitute an entirely new beginning for the Essex four-piece, while both paying lip-service to their roots and signalling a bright new future. This is the sound of a young band taking some gigantic risks and hearing them pay off, in some style. This is the moment they stand up and start fulfilling their potential.

So, after touring MTMT for over a year, hitting new peaks of commercial success and critical acclaim in the process, the band took their first significant break since they formed in Loughton in 2007. When they regrouped in 2014, they headed to Middle Farm Studios in Devon with long-time producer Peter Miles. But if that took them back to familiar ground, the music that emerged was anything but.

"We came to it like a blank canvas," says Liam. "We set ourselves up to really experiment and try and go somewhere else."

"We don't like being comfortable," adds Alfie. "We like to shake things up and put our personal character into the music. We didn't want to limit ourselves – we were trying to achieve something different."

And different Ark certainly is. Influenced by Seventies acts such as Led Zeppelin and Black Sabbath ("You listen to those records and they didn't have any computer wizardry," says Alfie; "There was a more real and personal element to that music"), We Are The Ocean resolved to play almost everything on the album live, as a full band. But, inspired by the pioneering spirit sparked in the studio, they also refused to be tied to a single sound, instead embracing whichever approach suited the collection of irresistible anthems they found themselves writing. Even if that meant going boldly where most bands fear to tread.

"We went through some periods in the studio where we were like, 'Is this too far?'" says Tom. "But then it all started to take shape."

"Most albums aren't very versatile," says Jack. "They find a formula and go with it, but we wanted to show our versatility. The gangsta rap song got cut, but other than that..."

Jack is joking, of course, but if the electric eclecticism of Ark is all about covering those bases, it covers them brilliantly. The vaulting space-age sounds of the title track is surely one of the most out-there songs to make it onto heavy Radio 1 rotation in recent years, after it caught Zane Lowe's ear when put out as a teaser track last year. When playing it for the first time as his 'Hottest Record In The World' Lowe enthused, "When you put that much into something and you believe in it that much that you are willing to step out of yourself and completely open yourself up and make music like that – you deserve to be applauded". Add to the mix the high voltage riffing of Shere Khan and I Wanna Be, and Ark has all the right rock moves in all the right places.

The end results are occasionally raunchy, often raw, but always real, as – given time and space to experiment – the band embraced the endless possibilities of their studio environment. Listen carefully to Hope You're Well and, as well as the band getting in touch with their inner Nineties power balladeers, you might just hear the raging storm outside as it was recorded in a late-night wine, whisky and weather-fuelled session. Analyse the beautiful acoustic sounds and lyrical emoting of Letter To Michael and you'll uncover a heart-felt tribute to Liam's father.

And listen to the whole album and you'll realise a band that played its part in moving the UK's burgeoning rock scene from niche underground concern to today's arena-hogging, playlist-bothering supernova, are back and in the mood to collect their dues. "There's an uprising against auto-tuned pop," declares Jack. "The rock sound is a lot more natural and people are starting to prefer that to The X Factor."

Here's hoping. But then WATO have been there, done that and sold a skipload of the T-shirts. At the start of the Maybe Today, Maybe Tomorrow campaign, they found themselves on a lengthy stint on the Vans Warped Tour in the US, enduring a baptism of fire as a four-piece in one of the most challenging touring environments out there.

Towards the end, after adjusting adroitly to their revamped line-up and gritty fresh sound, they threw themselves into supporting Muse in the enormodomes of Europe, getting an insight into what can be achieved with limitless ambition, unending hard work and access to dancing robots. And having come through both tests – and many more besides – with their reputations enhanced, We Are The Ocean are now in the mood to claim some of that for themselves. "Hell yeah!" declares Liam. "We want to be the first band to play on the moon. That's do-able, right?" Right. Because We Are the Ocean are done dealing in small steps. With Ark, it's finally time for their giant leap forward.