The Tigershark is one of only a few submersible units. Being submerged makes the unit invisible to radar and vision (unless revealed by sonar), as well as immune to most weapons. Only ships armed with torpedoes (the Destroyer, the Tigershark itself, and the experimental Wilfindja Sea Hunter) or other anti-sub weapons can engage a submerged unit. Use this fact to your advantage: most players will be completely incapable of engaging your subs, making the Tigershark an excellent scout and surveillance unit
Due to its low cost, the Tigershark is fairly weak in direct combat. Engaging any ship that can fire back one-on-one will probably result in a loss. Instead, use your submarines' low cost and mobility to bring several subs to bear on each enemy group, destroying one enemy ship at a time.
Surfacing your submarines will allow you to bring an additional weapon to bear. Surfacing makes the Tigershark vulnerable to surface weaponry, which cannot hit it while submerged. As such, use the cannon when engaging targets that cannot effectively shoot back, such as unupgraded naval yards or UEF cruisers, but staying submerged is usually a better choice.
In groups, Tigersharks can be very powerful sea-going tanks. The relatively low cost of a single sub makes building several Tigersharks viable in most situations, and clusters of these units can effectively engage most sea-going units, including even experimentals such as the Kraken.
Early game they are essential for sea superiority, as cruisers are weak in direct fights against mobile units. Mid game they are still an effective sea superiority unit and have a place beside battleships. They are almost wholly superseded by the Atlantis II.
Many times, if you surface, an eager opponent will bomb you to pieces, so try to keep submerged
Note: Even when submerged, they are still vulnerable to the Illuminate Loyalty Gun..
Surfacing near an enemy base for longer than a few moments will almost always result in death and disaster, so don't try.