Austrian Internet articles write more or less consistently about the fact, that nude hiking is permitted in Austria, but not on high-traffic routes. The police speaks of a legal limbo. Examples:

“Hier lässt man FKK freien Lauf" (wanderdoerfer.at)
[en: "Here, naturism has its free range"]

“Nacktwandern: Nicht erlaubt, aber auch nicht verboten" (heute.at)
[en: "Hiking in the buff: not allowed, but also not forbidden"]

“Nacktwandern: Textilfrei in den Bergen" (kurier.at)
[en: "Hiking in the buff: free of clothes in the mountains"]

All these sources do not state, on which legal basis the statement is made or whether it is merely the personal view of the author.

We have searched the Internet for relevant terms of Austrian police law on legal cases in practice. However, we found no case of hiking in the buff among the results, except for a young man, who strolled in the nude within a built-up area. All other examples involve completely different incidents and serve only, to give examples for practice concerning abstract concepts of law.

Decency in public

In Austria, a violation of conduct is a behaviour, that is grossly in violation of generally accepted principles of decency. The exposure of such a behaviour is punishable according to regulative law. The legal norms are defined in the respective police or security law of the federal states together with the regulative law. A precondition for liability is, that the punishable behaviour takes place in public, i.e. in a non-a priori limited group of people. That is to say, that beyond the circle of those involved, other people have the opportunity to perceive the behaviour. As examples of violations of decency are e.g. urinating in public, chanting the slogan “A.C.A.B.”, or show stink fingers. The punishments of decency violations are carried out or initiated in the first instance by bodies of the federal police. The minimum penalty is an administrative fine, in Austria called "penal order". A violation of decency is to be distinguished from a disturbance of public order.

Source: “Anstandsverletzung” (de.wikipedia.org)

Example: City of Salzburg

“Den öffentlichen Anstand verletzt, wer ein Verhalten setzt, das mit den allgemeinen Grundsätzen der Schicklichkeit nicht im Einklang steht und das einen groben Verstoß gegen die in der Öffentlichkeit zu beachtenden Pflichten darstellt, insbesondere wer […] öffentliche Einrichtungen wie Denkmäler, Brunnen, Sitzbänke oder Unterstände in anstößiger Weise nützt, etwa indem andere Personen am bestimmungsgemäßen Gebrauch dieser Einrichtungen, soweit ein solcher in Betracht kommt, gehindert werden.”"
[en: “Public decency is violated by anyone, who behaves in a way, which is not in accordance with the general principles of decency and which constitutes a gross breach of the duties to be observed in public, in particular anyone who […] uses public facilities such as monuments, fountains, benches or shelters in an offensive manner, for example by preventing other persons from using these facilities in accordance with their intended purpose, if such use is feasible.”]

Kommentar des Zeitungsreporters: “Man versteht, dass damit Punks, Bettler_innen und Rucksacktourist_innen gemeint sind."
[en: Comment of the newspaper reporter: “You understand, that punks, beggars, and backpackers are meant.”]

Source: “Die Anstandsverletzung (augustin.or.at)

Further untranslated examples

• Example: Steiermark / Styria
  “Die Anstandsverletzung” (augustin.or.at)
• Example: Linz
  “Polizisten ‘Oida’ genannt: LASK-Fan machte sich strafbar” (heute.at)

Conclusion

A deed of “violation of public decency” may even be applied in case of trifles. Whether this category may be assigned to walking in the nude, is difficult to predict.

Regulatory offence

In Austria, you use the term “Ordnungsstörung” [de: “Störung der öffentlichen Ordnung”; en: “regulatory offence”] for a punishable, particularly reckless behaviour, which disturbs the public order in a unjustifiable manner. A behaviour is to be rated as especially reckless, when one misses the consideration of legitimate interests of fellow human beings. In other words, it is such a kind of behaviour, that violates those unwritten rules for the behaviour of the individual in public, whose observance is regarded as an indispensable prerequisite for a thriving living together. However, a regulatory offence requires a “particularly” recklessness, which has to be assessed in individual cases. Anyone, who disturbs others when exercising or claiming their constitutionally guaranteed rights, behaves very ruthless in general. Anyone, who e.g. disturbs peaceful political events or the practise of religion, commits a regulatory offence.

Further examples for particularly reckless behaviour:

• name-calling
• loud yelling, screaming, and rioting
• screaming and gesticulation towards executive functionaries, if the behaviour is not to be assessed as “aggressive behaviour towards organs of public supervision or against military guards” according to section 82 SPG
• stepping with street shoes onto the seats of park benches

Such a behaviour constitutes a regulatory offence according to section 81 of the Security Police Act (SPG).

According to the "Verwaltungsstrafgesetz" [en: Administrative Penal Code], arrest might be a measure in the event of a disorder, if the disturber was caught red-handed and continues the behaviour in spite of a warning or attempts to repeat it. However, the organs of the public security service have to refrain from arresting, if this can be prevented by a more lenient means.

The more lenient means are either to send the disturber off the public place or to seize things needed to repeat the disturbance.

Source: “Ordnungsstörung” (de.wikipedia.org)

Example: A nude strolled through Steyr

Strange occurences in Steyr! Thursday afternoon, a brown-tanned, slender, and naked (!) man walked down the street completely serenely. Passersby called the police, who arrested the young nude because of a regulatory offence.

I was just on my way home, had to stop at the traffic lights and noticed the naked man, "says Jennifer Bartak towards "Heute" [en: "Today"]. From her car, she photographed and filmed the young man on his walk through Steyr, as the officers marched him off.

The 21-year-old has not commented on so far, why he was on his way in the nude. The police officers gave him emergency clothing. He shall be examined medically.

Source: “Nackter spazierte durch Steyr” (heute.at)

Further untranslated examples

• Wearing a printed T-shirt with an accusing slogan
  ”Anti-Scheuch-Shirt: Anzeige wegen Ordnungsstörung” (diepresse.com)
• New Year's Eve ”celebrated” with alarm guns
  ”Mit Schreckschusswaffen Silvester "gefeiert"” (orf.at)

Conclusion

The offence of “disturbance of public order” is rather used to maintain or establish peace and order between citizens or groups involved. Whether walking in the buff can be classified in this category cannot be reliably deduced from the example of "a young man walking in a built-up area”.

Justified (complaint of) disturbance

This is of all here analysed terms the most enigmatic one in Austrian law.

One reason is, that the Austrian term “berechtigtes Ärgernis” sounds for a German native speaker as contradictory as the literal translation “justified disturbance” for a English native speaker. That's, why we interpret it as "justified (complaint of) disturbance”.

Another reason is, that a “justified (complaint of) disturbance” cannot only be committed by sexual deeds in public (StGB § 218) but e.g. also by criticism of religion:

Section 188 StGB
Anyone, who publicly denigrates or mocks any person or thing, that is the object of worship of a church or religious society, which exists in Austria, or a doctrine, lawful practise, or lawful establishment of such a church or religious community, in a manner, which might cause justified (complaint of) disturbance, is to be punished by imprisonment of up to six months or a fine of up to 360 day rates.

Source: ”Ist §188 StGB verfassungswidrig?” [en: ”Is section 188 StGB unconstitutional?”] (konfessionsfrei.at, 2018). Pls note, that this webbsite meanwhile only redirects to facebook. We do not know, if the article found on konfessionsfrei.at in 2018 still exists.

A third reason is, that found examples look quite exotic. Therefore, natury in English summarises only the, perhaps, least exotic one.

Example: Jail for "looking wrong"?

• Jail for ”Looking wrong”?
  ”Eine Haftstrafe für ‘blöd schauen’?” (kurier.at)
  The basic idea of this article is, that Austrian police could arbitrarily fine people, who were, due to the personal opinion of police officers, molesting their work or the public order, until the 1970s. The article describes, that this legal measure has later been removed from Austrian law and is now, i.e. in 2016, when this article has been published, again in discussion to be reintroduced into the Austrian security police law. The article ends suspecting, that the main reason is to empower police, to be able to take measures against drug dealers at two of Vienna's subway stations, which – hold your breath! – do no longer exist!

Conclusion

The offence of "justified (complaint of) disturbance" is used very differently in Austria in various contexts, has been controversial since its (anew) introduction and is the subject of heated debate. Classifying hiking in the buff does not seem impossible in this category.

Unacceptable annoyance

Examples:

• Noise from a children's playground is not an unacceptable annoyance
  ”Kinderlärm: Keine ‘unzumutbare Belästigung’” (kurier.at)
• Unacceptable annoyance – last orders and closing time preponed
  ”Unzumutbare Belästigung – Sperrstunde vorverlegt” (pm-anwaelte.at)
• Barking lasting for hours: Deaf couple has to pay a fine of 300 Euro because of their dog
  ”‘Stundenlanges Bellen’: Taubes Ehepaar muss wegen Hund 300 Euro Strafe zahlen” (kurier.at)

Conclusion

The offence of ”unacceptable annoyance” mainly concerns immissions of noise or odours as well as pollutants such as smoke or soot. Hiking in the buff is therefore not expected to be classified in this category.

Bottom line

A look at the legal practice in Austria does not allow a clear statement on how simple nudity, such as hiking in the buff or nude sports, might be legally classified. This is probably also due to the fact, that hiking in the buff is perhaps hardly known in Austria (except NEWT for a week in the mountains once a year).