Exhibit 23 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in Registration Statement No's. 33-99112 and 333-6859 on Form S-8 of Monterey Bay Bancorp, Inc. of our report dated February 6, 1999, appearing in this Annual Report on Form 10-K of Monterey Bay Bancorp, Inc. for the year ended December 31, 1998. /s/ Deloitte & Touche LLP San Francisco, California March 30, 1999 40