According to Wikipedia, Elfstedentocht is pronounced [ɛlf'steːdə(n)tɔxt] and Alvestêdetocht [ɔlvəˈstɛːdətɔχt]. Elfstedentocht is close to how I'd pronounce it as a non-native German speaker, except I was pronouncing ‹st› as [ʃ] and ‹o› as [o] (my native dialect has the cot-caught merger, so I don't use ɔ). Alvestêdetocht isn't much different, except for the ‹A› as [ɔ] that I wasn't expecting.