A pair of second-hand
Type 214 U-boats would have been awesome.
Side question, why didn't Ukraine fight this hard and with this level of success in 2014 to hold Crimea? Instead the place flipped for the Russians faster than Kabul fell to the Taliban.
Well, I could write 100 pages about that, referring to my personal experience (born and grew up in Sevastopol)...
Alexander Nevzorov coined a phrase: "Ukraine was lying unconscious and the Crimea stack out of her purse".
Just some facts.
The occupation of Crimea began in February 2014 when the Russian GRU seized the Parliament building in Simferopol.
Ukraine was in turmoil. Top officials who ran away from Kyiv to the Russian Federation: President, Prime Minister, Ministers of Defence, of Internal Affairs, of Justice, of Finance, one or two vice-Prime Ministers, many deputies. Head of SBU (Security Service), etc.
The situation in Crimea:
Commander of VMSU (Ukrainian Navy) who was a top military commander in Crimea, took a "sick leave" and never returned to his office. His successor betrayed Ukraine on the 2nd day after the appointment. Heads of SBU, police, military intelligence, most of the top civilian officials, - all betrayed. About 70% of military personnel deserted and half of them joined Russian forces later. Figures were even higher in police and SBU.
Attempts to resist were chaotic, while the aggressor acted according to the well-developed plans.
Now, if you ask me why all that massive treason... Many articles and books were written about information warfare, about "Gerasimov doctrine", etc. But I'd suggest finding old lectures and interviews with
Yuri Bezmenov, it's a good start. Bezmenov's warnings are still valid, not only for Ukraine - for all world.