Studying the ecology of endangered species in portions of their range where the population remains abundant can provide fundamental information for conservation planners. We studied nesting by radio-tagged Marbled Murrelets (Brachyramphus marmoratus) during 2007 and 2008 in Port Snettisham, a relatively pristine, remote mainland fjord in southeast Alaska with high at-sea densities of Marbled Murrelets during the breeding season. Of 33 active Marbled Murrelet nest sites located during the study, we found 15 within forested habitat (tree nest sites), 16 in nonforested habitat (ground nest sites), and 2 that could not be determined. Some nests were located farther inland from the coast (range: 1–52 km) and at higher elevations (range: 42–1,100 m) than previously documented in Alaska. Nesting success to ≥20 days posthatch (0.20 ± 0.07 [SE]) was less than half of similar estimates in British Columbia and more comparable to estimates from California and Washington. A logistic regression found that nesting success did not differ between years, but nesting success was higher for tree nests than for ground nests. Conservation planners should consider that Marbled Murrelets will use certain nonforest habitat types for nesting in mainland southeast Alaska. Our reported nesting success was likely a maximum, and our results indicate that nesting success can be low even when nesting habitat is seemingly abundant and marine habitat appears excellent.