In the game, the player controls Merryn, a young girl who crafts a makeshift submarine to search for her father who went missing while fishing.

Song of the Deep has the player control Merryn, a 12-year-old girl who loves her father, a fisherman, especially when he tells her tall tales of his adventures.

Areas of the game's world require the player to locate special improvements for Merryn and her equipment to surpass obstacles and explore further.

Insomniac's chief creative officer, Brian Hastings, considered Song of the Deep as a "passion project",[3][4] wanting to create a heroine that his daughter could look up to.

[5] A further influence for the heroine was the favorable feedback that Insomniac has received over the years from fans, praising with how the developers were able to create characters they could identify with.

[9][10][11] Slant Magazine gave the PlayStation 4 version four stars out of five, saying that it was "uninspired only when it comes to its boss encounters, which end up being repetitive gauntlets of angry anglerfish enemies.

"[26] However, Metro gave the same console version six out of ten, calling it "A different take on the usual Metroidvania formula, but while the story and setting are charming the puzzles are rarely anything other than frustrating.