There was a mass drowning of 19 shellfish gatherers in Morecomb Bay in northwest England in 2004 - another extensive tidal flat. They were mostly immigrants who didn’t know the danger, and I believe their employer was held liable.
The Morecambe Bay walk is now a frequent charity event (for the excitement factor?) but is lead by a trained guide.
https://www.yourguide2thelakedistrict.co.uk/events-in-the-lake-district/morecambe-bay-walks/
And who would have thought the Queen has an "official Guide"?
Cedric Robinson MBE, the Queen's Official Guide.