Vickers Armstrong – now BAE Systems – built its first submarine in 1888 and has been in the forefront of submarine construction ever since. This is a review of the uses of welding in building submarines at BAE Systems, and shows that many of the problems of fabricating heavy, high-strength welds encountered and often solved, in advance of the rest of commercial fabrication.

The Beginnings
The first all-welded ship built in the United Kingdom was completed at Cammell Laird's shipyard, in Birkenhead, in 1923, but it was not until the late 1920's that electric welding was permitted in United Kingdom naval construction, and not until 1933 was electric welding used for naval construction.

Riveting remained the principal method of plate joining until the early part of World War II, despite the fact that Vickers' Production Manager Sir Len Redshaw had seen extensive welding in German submarine building in the late 1930's, and was desperate to increase it in United Kingdom.

I would have to say that World WarI submarines were riveted. I hope this help you in your question.