The song is an acoustic ballad that has been described as channelling Coldplay's earlier works, Parachutes and A Rush of Blood to the Head. The song is predominantly played with an acoustic guitar and a steady electronic drum beat, with a light orchestra accompanying the song towards the end. The song's second half merges into the next track from the album, A Sky Full of Stars. The song's lyrics, which share the same motif as the rest of the songs featured on Ghost Stories, deal with a troubled relationship.

The song was recorded by the band during sessions for their sixth studio album in 2013, at their purpose-built studios The Bakery and The Beehive in North London, England, both originally constructed for work on their two previous studio albums, Viva la Vida or Death and All His Friends and Mylo Xyloto respectively.

"Oceans" received positive reception upon its debut during the band's appearance on Live Lounge. Carolyn Menyes of Music Times, who described the song as "dreamy", wrote a positive review of the song, describing it further as "sleepy, comforting and straight up pretty in all the right ways; at least on the surface". Bruna Nessif of E! also wrote positively of Martin's performance of the song, writing that "there are notes Martin hits that are just incredible, and they sound just as amazing as they do while playing on repeat on your radio at home". Carl Williott of Idolator, upon mentioning comparisons of the song to Parachutes, wrote that the song "is the first track that truly feels like it could've come from a Parachutes session. There's hardly a hook to be found, but it's a lovely, slightly forlorn sway of a song, with an acoustic guitar anchoring Chris Martin's meandering falsetto amidst some swirling atmospherics". Alex Young of Consequence of Sound jokingly stated that the song would "make for a good Starbucks soundtrack".

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Wikipedia