From Helsinki to Stockholm is there an available route?

Sure. By land it's quite a long way. The most comfortable is probably by ferry, either Helsinki to Stockholm or Turku to Stockholm. The ferries only give a reduction but that also means you don't need to use a travel day if you don't use any trains on the day you leave with the ferry.

And since many, many years there are 2 competing ferries- Silja/STena and Viking-and most times the normal fares are even quite cheap. And esp. those all the way from HEL are excellent cruiseliners. They make their money from the ´skattefritt=taxfree’sales!

In fact one of these from Turku was ´free´ for IR-holders-but you still have to pay the porttax and the on night sailings obligatory bed/sleeper space

I just checked the prices. Now, for example, Helsinki - Stockholm Tallink / Silja costs 12 euros without discounts (a day trip without a cabin). Pretty affordable.