Boscastle Harbour blowhole — close-up!

(There's now an improved version of this recording, at https://freesound.org/people/Philip_Goddard/sounds/837369/ )
Fascinating — all these subterranean deep grunts to heavy wallops, most of which are each followed by a normally low-angle jet of sea spray; you can hear it splashing down as it projects out over the Harbour.

Boscastle Harbour blowhole (Cornwall, UK) is reputed to be active generally about two hours either side of low tide — but how long that activity lasts depends on both the size of the swell and what stage the tide is in. Neap tides will get the longest activity and spring tides the most transient activity. So I had to choose carefully to catch things right for a good recording. Seem to have managed it this time!

I made this recording early afternoon on 10 March 2015. As the activity lasted well, I assume it was neap tide at the time.

You'll note how a subterranean thump precedes each jet, which latter itself is quiet apart from the splashdown, so this must have a different mechanism to that of the Shag Rock headland's blowhole, near Perranporth, which makes a gruff heavy 'whoomph' accompanying the jet, and well captured in various recordings I've uploaded here.

Advisory

For a realistic effect, the playing volume needs to be set at 6dB higher than a sensible normal listening level.

High-grade headphones are particularly recommended in order to hear all the detail. Also, because the stereo imaging has been enhanced, that may cause a certain phasiness or phase cancellation points when you listen through certain speakers, whereas that effect doesn't occur when listening through headphones.


This recording taking place. The recorder's light grey furry windshield can be seen on the bare rock on the right, just beyond the grass. — and yes, it was precarious to get down there and place the recorder!

A wider-angle view of this recording taking place.

Techie stuff:
The recorder was a Sony PCM-M10, with just one furry windshield — a Røde DeadKitten (original, more effective, version).

Post-recording processing was to apply EQ in Audacity to correct for the muffling effect of the windshield, and more recent processing with the A1 Stereo Control VST plugin (200% widening).

Please remember to give this recording a rating — Thank you!