I understand that this is a joke about the Titan submersible incident, but shipwrecks actually kill people all the time, especially the deeper ones—the max depth is about 40m/130ft for recreational diving, and up to about 530m/1759ft for commercial divers. While all diving has its risks, shipwrecks are particularly dangerous because they're deteriorating hunks of metal underwater and often in relative darkness. A salvage diver in the Costa Concordia, for example, died after cutting his leg underwater and was unable to surface in enough time (source). Recreational divers have died after getting trapped inside wrecks, such as in the case of the USS Spiegel Grove in 2007, when three divers died doing a penetration dive (source). 7 other divers have also died on the Spiegel Grove,* and she was also cleaned out and sunk as an artificial reef, with fewer hazards than normal.
I don't know for sure what the wreck with the most diving fatalities is, but there are 26 associated with the Andrea Doria (source), which is often considered the "Mount Everest of wrecks" because of its depth (50m/160ft).
Some other wrecks with multiple diving fatalities:
- RMS Empress of Ireland – 6 as of 2009 (source)
- HMCS Yukon – 5 as of 2012 (source)
- HMS Scylla – 4 as of 2021 (source), also sunk as an artificial reef
*The Spiegel Grove actually sank accidentally before she was fully prepared and landed on the seafloor upside down. She was later rolled onto her starboard side by a salvage company. Fun fact: in 2005, Hurricane Dennis created such strong waves and currents that it actually fully righted the Spigel Grove, like she was originally supposed to be sunk.