Now, a second video has appeared.
It does appear to show something big in the river, and that thing does look like whatever was in the first one.
"Have you ever noticed that supernatural sightings are a bit like London buses? As soon as one piece of 'evidence' emerges, more follows shortly after.
"That has very much been the case with the sighting of the 'Loch Ness Monster' in the Thames this week.
"On Tuesday, a video surfaced showing a dark object moving through the river near the O2 Arena.
"It was shot on April 1, but that didn't stop loads of people coming to the conclusion it was a creature that hasn't even been found where it is supposed to live.
"And now, sure enough, a second bit of footage has been posted online.
"Ot was uploaded to YouTube yesterday by user Lea K, and bears a passing resemblance to the first video shot from an Emirates cable car as it passed overhead."
You can watch both videos below.
Video 1, uploaded to YouTube March 27
"This was on the cable car in Greenwich yesterday. something huge was moving under the water and then briefly surfaced. Are there whales in the Thames? Or is it some weird submarine."
Video 2, uploaded to YouTube on April 9
"ANOTHER NESSIE SIGHTING? #tessie
"(everyone was looking at a freaking rainbow and no one paid attention to this thing.. its probs just rubbish haha)"
To me, the videos do seem to show something real. As to what that something is, I don't know. The uploader of the first video says "Are there whales in the Thames?" The thing almost looks like a whale (and it's definitely big enough to be one). But is it?
Or is it, as the Metro jokingly says, is it the "Loch Ness Monster" in the river?
You can go to the Metro and vote what you think it is by clicking the link above. Their options are (again, jokingly) "I'm now 110% sure it's the Loch Ness" or "Umm…"
I think it may be a whale. I guess we'll just have to see if any more reports come in.