I am traveling to ONP in late July and would like to ask those of you who know how long the Bainbridge Ferry and the Keyport Ferry wait times are.

My flight is leaving on late Sunday night (I know its bad) but how bad is it to get back to Seattle?

I've seldom if ever had to wait more than one boat (ca. 40 min.) for the Bainbridge boat, and rarely that.

Only Keyport ferry I know of serves NYC. Do you mean Keystone? Are you coming from Whidbey or the Olympic Peninsula? If you're using the Port Townsend - Keystone ferry then you have no need for the Bainbridge ferry, only the Mukilteo ferry at the south end of Whidbey.

If you're coming from Port Townsend to Seattle via Bainbridge, there's no need for the Keystone ferry; you just drive over the Hood Canal Bridge, turn right at the end, and aim for the Bainbridge boat.

And the answer is that the PT - Keystone run is one of the least reliable in the system - oldest boats (kinda quaint) and shallow moorages, making for tide delays some times. If time is a concern, I'd stick to the main routes like Bainbridge or Edmonds.

Eastbound ferries on summer Sunday afternoons can be pretty crowded. I'd drive around (i.e. down Highway 3 and 16 to the Tacoma Narrows Bridge), then up to Seatac.

You shouldn't have to wait more than one boat, maybe two at the most, but when a flight's involved, I would drive around through Bremerton and Tacoma rather than taking the ferry unless you plan to come back to Seattle quite a few hours in advance of your flight. That might be your best bet if you do want to take the ferry--plan on coming back Sunday afternoon and having dinner downtown before heading to the airport.

You should look at the WA State Ferries website for the next few Sundays and see how the wait is.

I agree with the above ideas to drive around instead of ferry, and/or come back into Seattle with enough time for a meal before heading to the airport.

The OP asked about coming back to Seattle, not Sea-Tac.

If it's a late departure (read, redeye) then I don't see the point of "driving around" unless the $15 or so for the ferry is a consideration (remember no passenger fees eastbound, just the car fee) - which should be offset against additional fuel cost for the extra driving, plus the $3 toll for the new bridge, which hopefully will be open by the end of July (and if not traffic will be a consideration.)

I for one find the drive around tedious - traffic around the bridge and Nalley Valley, construction on I-5 in the Tacoma corridor, boring drive north through un-scenic Fife and Federal Way... but just IMO. Set against a late-evening entry into Seattle on the Bainbridge boat, with the sun behind the mountains and/or shining off the downtown high-rises... no contest.

Unfortunately, nobody knows how long the wait for a ferry will be. The end of July is a busy time for ferries.

If you get to the ferry 45 minutes early and miss the ferry you want and then wait another 45 mintutes for the next ferry, the 30-minute crossing could end up costing you two hours (45+45+30=120).

If my destination were SeaTac, and I wanted to make a relatively accurate estimation of travel time, I would drive there via the Narrow Bridge and Tacoma.