Took the Friday Harbor ferry from Anacortes to try to see some Orcas at the park. Be warned that the ferry over is pretty pricy--we traveled with 2 adults and 4 kids and our usual cost of about $20 for a one-way ferry ride was increased to $100 for a round trip. It could have been a holiday (Labor Day) cost increase, but I was shocked nonetheless.
The park is surprisingly beautiful--big meadows interspersed with gorgeous evergreens and madrona trees, rocky bluffs, and pebbly beaches scattered with driftwood. There is an info center where you can purchase a day or annual Discover Pass with a credit card. I don't recall what its hours are, but if it's closed there is a self-service station where you can get a day pass for exact change (cash only, possibly checks, too).
There is a large loop trail that takes you just outside of the park and crosses the road and turns back into the park to loop to your starting point. There are many side trails that cut across various parts of the park, and a lighthouse to explore. I'd say there is much more than 1.5m of trail in the park. I took the kids down to Dead Man's Bay and my friend took them up to the lighthouse. It looks like there is a trail outside of the park, high across some meadows that face the water, but we didn't have time for more exploring in order to make our reserved return ferry trip.
The Friday Harbor ferry is quite busy, apparently, and reservations are encouraged. I would suggest giving yourself as much time as possible because there is much to explore in the park, on land outside of the park, and in Friday Harbor--a whale museum and lots of shops and restaurants.
Almost forgot to add--wasps were a major annoyance, as they seem to have been all summer, everywhere I've been. My son was stung three times on one finger while exploring the rocks below our picnic table where we were planted to watch for whales. While the sun was out, the wasps were incessant, and when the sun was clouded and it cooled off the wasps stayed away. I cannot tell you how sick to death I am of wasps this year.