The area of investigation lies between lat. 56°-59° N. and long. 134°-137° W. This coastal region consists of a complex of fiords, estuaries, channels, and straits. Samples from standard hydrographic depths were collected from 50 stations occupied every 2 months during 1965-1966. Cores and grab samples also were retrieved to study the lithologic character and interstitial water composition. Samples from major rivers and streams were also collected.

The period of collection included two seasons when blooms of diatoms were noticed in the inlet waters. Silica concentration between blooms varied at different depths with the maximum at the surface and minimum at the bottom. The silica-salinity ratio diagram indicated fresh water as a minor source for silica during summer months. However, during winter months, the silica seems to recycle from deeper waters to replenish surface silica removed by siliceous organisms.

Approximate estimations of silica utilization during diatom blooms were made by silica-salinity ratio diagrams. The removal of silica during the September, 1965, bloom appeared to be 12 per cent of the total amount of silica present in the system during the month of November, 1965 (low biological activity).

The vertical distribution of silica in glacially-fed areas such as Glacier Bay showed a homogeneous mixing with no sharp halocline throughout the year. Chatham Strait, on the other hand, was stratified during the summer, and there was no sharp halocline during the winter months.

The silica concentration in interstitial waters showed a higher concentration in basins with finer sediments and lower concentrations in basins located near the source with coarser detrital sediments. No relation between silica and major ion concentration in interstitial waters was observed.

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