As detailed as possible - including streams, lakes, rivers, trails, and elevation changes.
In data.gov, you can find shapefiles and other data on national parks. Here's a link to the datasets for Katmai National Park
As a little extra, here's a link to the National Park Service's webpage for the park. No shapefiles, but has photos and live webcams:
This is a link to Alaska State Geo-Spatial Data Clearinghouse:
This is a link to Alaska Division of Geological & Geophysical Surveys. Anything you can't find otherwise, you probably can get by contacting them.
nps search has over 2000 hits for Katmai, although not sure how many are shapefiles