Have you spotted the horsemen of the apocalypse in the Thames?

If you look closely at the river Thames, you'll probably spot a few rogue objects floating about - mostly old crisp packets and empty beer cans. But now there's a couple of apocalyptic horseman lurking in the depths of the dirty old river, too. The four figures are part of an installation called 'The Rising Tide' by underwater eco-sculptor Jason deCaires Taylor. But blink and you'll miss them, because the statues are only fully visible twice a day at low tide – the rest of the time they get submerged in the river as the tide goes in and out, until all that's left is their creepy floating heads.

To make things even weirder, the three-metre tall horses have oil pumps instead faces – as the artist wants to raise questions about our dependence on fossil fuels. The sculptures will be horsing around in the Thames until September 30, but get down there at low tide if you want to see them up close and don't fancy diving into the river.

Check out the best Instagram snaps of the ghostly horsemen:

 

A photo posted by The Communication Group plc (@tcg_pr) on Sep 2, 2015 at 1:29pm PDT

 

A photo posted by Lisa Jo Robinson (@gingerrobbo) on Sep 3, 2015 at 5:43am PDT

 

A photo posted by Yvonne Jacob (@jvonneyacob) on Sep 3, 2015 at 11:53am PDT

 

A photo posted by Andy Brittle (@andybrittle) on Sep 3, 2015 at 11:49am PDT

 

A photo posted by Paul SW11 (@paul_sw11) on Sep 2, 2015 at 3:23pm PDT

 

A photo posted by Miranda Nagalingam (@miranda_79) on Sep 3, 2015 at 8:38am PDT

 

A photo posted by jojocmorris (@jojocmorris) on Sep 2, 2015 at 4:24am PDT

'The Rising Tide' is part of the Totally Thames festival, which is on until September 30.