You did not identify a year of this divorce.I'm "Guessing" it was for your parents ?"IF" they divorced in Whatcom county, those records would be in Whatcom County Superior Court.The Superior Court Clerk has been responsible for keeping court documents under Washington State law for the period going back to Statehood (1889).
You can first try this site to identify the case number.http://dw.courts.wa.gov/http://dw.courts.wa.gov/ Do a Name Search.If you do find the correct people, that case number is important.
If you can't find the case number, or need help to obtain copies, go to: http://www.co.whatcom.wa.us/superior/index.jsphttp://www.co.whatcom.wa.us/superior/index.jsp The Court Clerk will help you by phone or email.They will charge for copies.I don't know what exactly you may need.If you need ALL the filings in the case, there may be limited filings, or in a severly contested case MANY filings.Each filing may be 1 page of nothing of importance (lawyer unavailable, one of the witnesses unavailable, etc), or it could be the original petition, or terms of child care, or final decree, which may be extensive.I would suggest you first obtain the listing of filings, then decide which you need.
Do NOT ask a genealogical society to obtain copies of marriage records from the county auditor/recorder.Go directly to that office.http://www.co.whatcom.wa.us/auditor/auditor_contacts.jsphttp://www.co.whatcom.wa.us/auditor/auditor_contacts.jspThey can advise if the marriage certificate was recorded (probably for free).If not, they can provide information on its location if known.I would send an email to the Recording Division: Recording@co.whatcom.wa.us