Tsunami is an all water map with four main islands for bases and a few other islands without anything on them. This is as naval of a map as they come, there is no access to the different islands except by water or air. Which means that the soviets are at a huge disadvantage when playing on this map. Tsunami can be played in battle, free for all, or naval war game modes. In battle and free for all, you can build all units available to a player. In naval war game mode you can only build land anti air units(i.e. ifv's or flack tracks) and only certain infantry units. There are several smaller islands around the main islands, these do not have anything on them and some cannot fit a mcv to build off of. However, the are ideal for stationing units to help assist your naval assault. On each island is are two beach access points, everywhere else there are cliffs. Also on each island there are two oil derricks.
There are a total of eight oil derricks, two on each main island. Other that that there are no other tech buildings.
Team Selection I would strongly recommend that you do not use the soviets on this map, especially on battle or free for all mode, because the allies have the nighthawk helicopter, which can transport up to five infantry at time. Which allows the allies to be able to secure other islands even if they do not own the seas. Also, I like to deploy g.i.'s on the smaller islands and have my naval battles near them so they can help me fight off my enemy. The other reason I would not use the soviets is because the allies have the gap generator which protects their base from assault from aircraft carriers or dreadnoughts and the soviets do not have anything to scout the enemy base except a Kirov, which is rather slow. Combined with the overall allied advantage in the naval category and the allies have a huge advantage over the soviets.
Allies: I would only recommend using America or Korea on this map, because the american player can: secure ore and tech buildings, assault a poorly defended base, assist in naval battles near shore, and provide glimpses into a shrouded enemy base for naval bombardment. And Korea because: Only available air unit in naval war game mode(besides hornets and dreadnought missiles), powerful can help neutralize surface fleet, can assault enemy harvesting, and base, and can uncover gap generator protected base for naval bombardment. France I would not use because the main surface ships(aircraft carrier and dreadnought) has better range than the grand cannon and a well placed paradrop could end having you destroy your own base, however it does provide excellent protection from amphibious assaults. But I believe that the negatives out way the positives of using this team. Britain and Germany serve no purpose on this map, their special weapon is neutralized by the seas, so I would would advise you to avoid using them.
Soviets: The soviets are so helplessly out gunned on naval maps that it is not funny, if you ever want to get back at a soviet player that's beaten you five trillion times using the rush this is the map to do so. The only bright spot for the soviets is the Iraqi desolator which can protect the beaches and help protect your base from invaders, also on a soviet vs. soviet game the desolators can destroy a dreadnought missiles before they are launched, so you can turn the tide of a naval battle pretty quickly if you use them properly.
On each main island there are two ore mines that provide a generous supply of ore, initially. Also there are two oil derricks as mentioned above, these are nice bonuses, but do not become reliant on them or you will be soundly disappointed at how little they give you. However, you would be surprised how quickly three to four miners can clean up the available ore, so you must secure extra ore early and then hang on to it. If you are able to secure half of the extra ore then you are in good, but if you can get all of the extra ore and hang on to it then you it is your match to win or lose. Here the allies have an advantage to because if they have a ore refinery on separate islands they do not require a transport to cross the can "chrono shift" over to their destination. This especially helps that you don't have to stop building naval units to build one stupid transport that you'll never use again.
The first order of business on this map is to establish a navy, not a big one, but you MUST have a few(2-4) naval units for scouting and initial defense of your territory, do not spend too much on navy early on I only build two to three naval units early then once I get a steady production do I start cranking out the naval units. The next order of business is to secure your beaches. Note: watch out for an early transport filled with dogs and engineers, if you don't have any defense, it does not matter how good of a navy you have if you don't have any buildings to defend. Next you need to expand to the other islands to secure more ore. There is only a limited amount of ore on each main island and once its out, its out, but if you already have a mining operation underway when your first supply does run out then you wont be stuck for a few minutes waiting for you mining operation to gear back up while your opponent is building towards your destruction. Once you have secured your island and your ore supply start cranking out the naval units, I'd suggest building about three to five naval yards(if you can afford them). Once I beat two people by myself because I had five naval yards pumping out units to their combined two. Then when you feel you have the naval edge over your adversary make your attack. I'd suggest not throwing all of your units in the mix at once, make your enemy commit to your initial force, then strike with your second wave. Note: the defender has the advantage because his units are already in a square, while yours are making their way single file. so move your fleet little bits at a time to avoid disaster.
Tips for defending: Line submerged units against the shore that way when your enemy passes by you will have the advantages of getting the first few shots off. Also, take advantage of land based units to help with your defense, deployed g.i.'s can be very devastating if the attack ignores them and if not then it distracts them from your fleet which allows you time to counter-attack. Once you have destroyed the enemy fleet and production yards, then move your heavy hitters in, just be sure they they have ample defense around them. Usually once the enemy has lost his fleet and realizes he can not re-establish it they will usually surrender, if not then use paratroopers, or black eagles/harriers to get a peek inside, once you can target just one structure or unit, then everything is up for grabs.
Sample Build Orders
Powerplant » refinery » naval yard » barracks » airforce command center » war factory » refinery