“My diving school has gone under”

A company that’s bankrupt and closes is said to have “gone under” (as if buried). There are several diving company/school jokes.
 
“Friend’s had to cancel his deep sea diving holiday - company went under…” was posted on Twitter on January 17, 2011. “Got a load of Scuba stuff from a bloke who’s diving company went under” was posted on Twitter on April 9, 2017.
 
“I used to work in a diving school, but the company went under” was posted on Twitter by Joe Bor on January 7, 2012. “My scuba diving school has gone under. #Dailypun #1Pun” was posted on Twitter by Tog1989 on May 12, 2016.
 
“The first submarine sandwich shop opened in 1898, but the store went under” is a similar joke.
   
         
Twitter
☢ Be Faithful ☣  ☄
@D3mon_Soul
Friend’s had to cancel his deep sea diving holiday - company went under…
4:18 PM - 17 Jan 2011
 
Twitter
Joe Bor
@josephbor
I used to work in a diving school, but the company went under.
4:44 PM - 3 Jan 2012
 
Twitter
Tog1989
@tog1989
My scuba diving school has gone under. #Dailypun #1Pun
4:34 AM - 12 May 2016
     
Twitter
CASIONOVA ♻️
@casionova90
Replying to @artichokebistro @EllennBrownn @GhastlyPriest
Got a load of Scuba stuff from a bloke who’s diving company went under
3:10 PM - 9 Apr 2017
 
Twitter
Tog1989
@tog1989
My diving school has gone under.
#badjokethursday
2:41 AM - 5 Jul 2018