*136OPINION OF THE COURT BY
LUM, C.J.The issue in this appeal is whether two published notices of public hearings on proposed rules and amendments of the Rules of the Hawaii State Park System prohibiting nudity in state parks, promulgated by the Department of Land and Natural Resources (DLNR), conformed to the applicable provisions of the Hawaii Administrative Procedure Act, Hawaii Revised Statutes (HRS) Chapter 91 (HAPA). We conclude that the notices failed to reflect the “substance” of the proposed rules and amendments as required by HRS § 91-3,1 and reverse the Defendant’s conviction.
I.
The initial notice appeared in the Honolulu Star-Bulletin on June 18, 1971, and merely stated that the DLNR would conduct public hearings regarding “Board Resolution No. 1 providing for the Regulation and Control of State Parks, Outdoor Recreational Areas and Historic Sites.” Hearings as publicized were conducted throughout the State on July 6,9,15, and 16, *1371971. The second notice was published in the same newspaper on April 7, 1981, and advertised public hearings scheduled for April 28,29,1981 and May 4,5,1981. The notice publicized department proposals to recast the DLNR rules in a new format and to make “substantive changes to existing rules.”
On March 8,1987, a Department of Conservation Enforcement Officer observed the Defendant-Appellant Peter D. Rowley (Appellant) to be completely nude at Pu’u ’Ola’i, Makena State Park, commonly referred to as “Little Beach” or “Small Beach.” The Appellant was in an area where posted signs warned beach users that “NUDITY IS PROHIBITED.”
Shortly thereafter, Maui Police Department Officers arrested Appellant for nudity in state parks. Appellant was charged and convicted for violating Rule 13-145-35 of the Hawaii State Park System which prohibits nudity in state parks. Use of the public beach at Pu’ u ’Ola’i, Makena State Park, has been the site of frequent arrests giving rise to prosecutions for violations of various state laws prohibiting public nudity. This appeal, however, presents the first instance of prosecution for violation of an administrative rule prohibiting nudity.
II.
The sole issue in this case is whether the DLNR’s adoption of State Park Regulation 2.32 (1971) and the successor DLNR Rule 13-145-35 (1981) prohibiting nudity in state parks satisfied the substantive public notice requirement of the Hawaii Administrative Procedure Act, HRS § 91-3.
HRS § 91-3 demands advance notice of an administrative agency’s plan to adopt, amend, or repeal its rules. The statute clearly and unambiguously requires that the notice “shall include a statement of the substance of the proposed rule” to “afford all interested persons opportunity to submit data, views, or arguments, orally or in writing.”2 HRS § 91 — 3(a)(1) and (2). The express legislative objective of the HAPA rule-making procedures is to provide for public participation in the rule-making process, by allowing any interested person to petition for a change in the rules as *138well as to participate in a public hearing. Hse. Stand. Comm. Rep. No. 8, in 1961 House Journal, at 655. Furthermore, the legislature has determined that “an agency must consider the views of interested persons where it seeks to promulgate a ‘rule,’ no matter how complex is the data that goes into the rule’s formulation.” Aguiar v. Hawaii Hous. Auth., 55 Haw. 478, 487-88, 522 P.2d 1255, 1262 (1974).
In Costa v. Sunn, 64 Haw. 389, 642 P.2d 530 (1982), we considered the issue of HAPA violations in amending welfare rules and held that the published notices of public hearings on proposed amendments to rules of the Department of Social Services and Housing were inadequate under HAPA. Contrary to the requirement of HRS § 91-3, the notices at issue “stated little more than the headings of the new rules and did not provide interested persons with sufficient information to direct their comments toward concrete proposals.” 64 Haw. at 394, 642 P.2d at 534. We explained that the “substance” of a proposed rule “means not merely the subject of it, but an intelligible abstract or synopsis of its material and substantial elements.” Id. Viewed in this light, the notices in question were inadequate.
As in Costa, both the 1971 and 1981 notices merely stated the general description of the proposed rules and amendments and failed to provide interested parties with sufficient information to allow for criticism, recommendations or formulation of alternatives. Neither a synopsis of material elements or an intelligible abstract was provided to afford interested persons the opportunity to present responses to the proposals. Consequently, the purpose of HRS § 91-3, to fairly apprise interested parties of proposed rules and amendments so that they can formulate and present rational responses to such proposals, was not served.
The State concedes that the 1981 Rule was not adopted in conformity with the public notice requirements set forth in HRS § 91-3, but argues that such notice was not necessary since no substantive amendment to State Park Regulation 2.32 (1971) was contemplated. We disagree. Before Defendant can be successfully prosecuted under an administrative rule prohibiting nudity in state parks, the rule itself must be promulgated in compliance with the rule-making procedures of HAPA, HRS Chapter 91. Since the adoption of the 1971 State Park Regulation was invalid and unenforceable ab initio for failure to comply with the substantive notice requirements of HRS § 91-3, the 1981 successor DLNR Rule, also concededly promulgated with inadequate substantive public notice, is similarly invalid.
*139Anthony L. Ranken, for Defendant-Appellant. James B. Takayesu, Deputy Prosecuting Attorney, for PlaintiffAppellee. Johnson H. Wong and Randall Y. K. Young, Deputy Attorneys General, for Amicus Curiae Attorney General, State of Hawaii.Reversed.
HRS § 91-3 provides in relevant part:
Procedure for adoption, amendment or repeal of rules, (a) Prior to the adoption of any rule authorized by law, or the amendment or repeal thereof, the adopting agency shall:
(1) Give at least twenty days’ notice for a public hearing. Such notice shall include a statement of the substance of the proposed rule, and of the date, time and place where interested persons may be heard thereon. The notice shall be mailed to all persons who have made a timely written request of the agency for advance notice of its rulemaking proceedings, and published at least once in a newspaper of general circulation in the State for state agencies and in the county for county agencies.
(2) Afford all interested persons opportunity to submit data, views, or arguments, orally or in writing. The agency shall fully consider all written and oral submissions respecting the proposed rule. The agency may make its decision at the public hearing or announce then the date as to when it intends to make its decision. Upon adoption, amendment, or repeal of a rule, the agency shall, if requested to do so by an interested person, issue a concise statement of the principal reasons for and against its determination.
We are not addressing here the issue of emergency rules which may be adopted without prior notice or hearing pursuant to HRS § 91 — 3(b).