# What were the unexplained deep sonar contacts? · Loch Ness

> Four answers have been proposed. None is ahead on the evidence yet. Four are still possible.

Source: https://mysteriesdept.com/mysteries/loch-ness/questions/QST0CRFXATA5QK8/what-were-the-unexplained-deep-sonar-contacts  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  
Updated: 2026-10-26T11:57:53+00:00  

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# What were the unexplained deep sonar contacts?

Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·Part of [Does Loch Ness hold a large animal unknown to science?](https://mysteriesdept.com/mysteries/loch-ness/questions/QST0CRFXA2W308J/does-loch-ness-hold-a-large-animal-unknown-to-science)·4 answers·0·0 following

**Four answers, none ahead** None is ahead yet. See what would settle it.

 

## Where it stands

Four answers have been proposed. None is ahead on the evidence yet. Four are still possible.

## Why it matters

Sonar contacts are the main physical records that searches have not explained; Operation Deepscan logged three that were stronger than fish and deeper, and vanished when revisited⁠[[1]](https://mysteriesdept.com/sources/SRC0CRFX1HE49S7/operation-deepscan). Tour-boat sonars continue to log deep contacts⁠[[2]](https://mysteriesdept.com/sources/SRC0CRFX3FY6XXX/the-official-loch-ness-monster-sightings-register).

## Answers 4



[**A large unknown animal.** ](https://mysteriesdept.com/mysteries/loch-ness/answers/ANS0CRFXJMA1EM2/a-large-unknown-animal)

Failed a test; not refuted outright

Evidence: 1 against

Disputed



[**Acoustic artefacts or transient objects (fish schools, thermocline returns, side lobes, debris).** ](https://mysteriesdept.com/mysteries/loch-ness/answers/ANS0CRFXJ4P341Q/acoustic-artefacts-or-transient-objects-fish-schools)

Not tested enough to call either way

Evidence: 1 for

Still possible



[**None of these.** ](https://mysteriesdept.com/mysteries/loch-ness/answers/ANS0CRFXK3Y528T/none-of-these)

Not tested enough to call either way

Evidence: none yet

Still possible



[**Seals that have entered the loch from the sea.** ](https://mysteriesdept.com/mysteries/loch-ness/answers/ANS0CRFXHD82F8Z/seals-that-have-entered-the-loch-from-the-sea)

Not tested enough to call either way

Evidence: 1 for, 1 against

Still possible

## History

1. 26 Oct 2026Asked on this site

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Where it fits

Loch Ness

[**Does Loch Ness hold a large animal unknown to science?** ](https://mysteriesdept.com/mysteries/loch-ness/questions/QST0CRFXA2W308J/does-loch-ness-hold-a-large-animal-unknown-to-science)Key question · No large unknown animal lives in the loch; occasional large visitors (seals) and known species account for…

**What were the unexplained deep sonar contacts?** You're here · 4 answers, inconclusive

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