If you are arriving by plane, you will most likely land at the Helsinki-Vantaa International Airport. Unless you wish to truly travel in comfort regardless of the cost, we do not suggest taking the taxi. The fare will likely be in the €40-€50 range per ride.

Renting a car is relatively expensive and not recommended unless you also bring a GPS navigator. (Some rental cars may include one, but don’t rely on it.) There’s an excellent public transport system in the area. Finnish taxis, the subway, trams, and buses are all very safe and reliable.

You will find all about the local public transportation (except for the taxis) at this website: Helsinki Public Transportation 

Also, this Wikipedia page might prove useful: Public Transportation in Helsinki

If you have a smartphone, there’s an excellent application, ”Andropas” by Akiware, designed to help traveling in Helsinki-Espoo-Vantaa region. You can find and download it from the Android Market.

The Journey Planner is a very helpful tool:

Choose “From: Airport, Vantaa” and “To: Dipoli, Espoo”, and you’ll end up right next to Dipoli. Which bus(es) to take depends a bit on when you’re arriving. Generally, you take bus #615, get off at “Mäkelänkatu”, and switch into bus #506, but there are other options.
You need to switch to another bus on the way, but when buying the ticket to the first one at the airport, tell the driver, just in case, that you need to get to Otaniemi, Espoo.

You only need to pay once, and then just show the receipt in the next bus. Switching is free within an hour or so.
This way, you can get to Dipoli conference center (or back to the airfield) for 4,50 euros per person. The travel time is about an hour.

NOTE: Bus drivers are not obliged to accept banknotes bigger than 20 euros!

If you want to go to Helsinki:

If you also plan to travel to Helsinki and see the sights and whatnot, you can opt to buy a regional ticket for 1-7 days (regional ticket means it’s valid in Helsinki, Espoo and Vantaa: Dipoli is in Espoo, a city next to Helsinki, and the airport is in Vantaa, another neighboring city). With a regional ticket, you can use public transport as much as you want to. (Not taxis, though.)

You can buy all sorts of tickets, including regional tickets, from the bus. The Helsinki Card is nice, but it doesn’t give you free transport to Espoo and Vantaa.