This paper describes some preliminary results of the cooperative effort between SACLANT Undersea Research Centre and Harvard University in the development of a regional descriptive and predictive capability for the Strait of Sicily. The aims of the work have been to: 1. determine and describe the underlying dynamics of the region; and, 2. rapidly assess synoptic oceanographic conditions through measurements and modeling. Based on the 1994-1996 surveys, a picture of some semi-permanent features which occur in the Strait of Sicily is beginning to emerge. Dynamical circulation studies, with assimilated data from the surveys, indicate the presence of an Adventure Bank Vortex – ABV., Maltese Channel Crest – MCC., and Ionian Shelf Break Vortex – IBV. A schematic water mass model has been developed for the region. Results from the Rapid Response 96 real-time numerical modeling experiments are presented and evaluated. A newly developed data assimilation methodology, Error Subspace Statistical Estimation – ESSE. is introduced. The ideal Error Subspace spans and tracks the scales and processes where the dominant, most energetic, errors occur, making this methodology especially useful in real-time adaptive sampling. q1999 Elsevier Science B.V. All rights reserved.