There are several transportation options going between Whittier, Seward, Anchorage, and Prince William Sound on a daily basis during the summer, and limited options in the winter.
Here is a list of companies that provide transportation services between Anchorage, Whittier, Seward, and in Prince William Sound:
There may be more transportation/shuttle services available since some people may have recently started a new transportation business.
Driving to Whittier? Please visit the Anton Anderson Memorial Tunnel's website for more details on schedule and tolls: http://www.dot.state.ak.us/creg/whittiertunnel/index.shtml