Previous investigations on Saterland Frisian report a large vowel inventory, including up to 20 monophthongs and 16 diphthongs in stressed position. Conducting a cross-dialectal acoustic study on Saterland Frisian vowels in Ramsloh, Scharrel, and Strücklingen, the objective is to provide a phonetic description of vowel category realization and to identify acoustic dimensions which may enhance the discrimination of neighboring categories within the crowded vowel space of the endangered minority language. All vowels were elicited in a /hVt/ frame. Acoustic measurements included vowel duration, mid-vowel F1 and F2, and the amount of spectral change and the spectral rate of change. The results suggest instances of phonetic attrition, i.e., merged categories, precisely where contrasts were reported to be on the retreat. The cross-dialectal comparison showed differences between the three dialects primarily within the F1 dimension at the 20% measurement point. The findings presented here contribute to the description of an endangered minority language and add to the question of which acoustic variables are used in languages with large vowel inventories to maintain or enhance the existing contrasts. Furthermore, the results underline the importance of the consideration of inter-speaker variability as well as measurements beyond the vowel target.