War Is Boring has a an excellent writeup on one such idea – the steam-powered submarine. If you wanted a fast naval vessel during World War I, oil-fired steam turbines were the cutting edge, capable of accelerating the British Royal Navy's nearly 19,000-ton HMS Dreadnought to speeds of 21 knots. So naturally, the Royal Navy thought, fitting that tech to a sub would be a recipe for a high-speed scout/hunter.
The problems with the Royal Navy's K-class subs were legion, though. While they were quick, capable of hitting 24 knots while surfaced, the unique requirements of steam turbines meant that these boats were also huge. They were nearly as long as today's Los Angeles-class nuclear attack subs, but they were nowhere near as agile. The bigger problem, though, was that lowering their large smokestacks and rig the ship for diving took a full four minutes. The ship was essentially a sitting duck during this time. If that weren't a big enough issue, the subs were also known to dive too quickly, and there were a number of incidents, some comical – imagine, if you will, a sub's stern and propellers sticking clear out of the English Channel – and others tragic.
War Is Boring's recap of these events is worth a read, and includes just why the Royal Navy thought the K-class was a sound idea, despite First Sea Lord Adm. John Fisher calling the fitment of steam turbines to a sub "the most fatal error imaginable." Of course, as WIB points out, steam power has been validated – every nuclear-powered vessel sailing the seas today is essentially a steam ship. Head over and have a look.