By looking at penal law, we see, that simple nudity is not a criminal offence: In penal law, all offences, that may be related to nudity, concern sexual deeds in public, only. Conclusion: In Germany, penal law is not applicable to mere nudity (as in nude sports, nude hikes etc.).
Terms such as "public disturbance" or "exhibitionism", which uninformed fellow citizens willingly cite, solely concern sexual deeds and have absolutely nothing to do with nudity in terms of naturist activities. Unfortunately, these uninformed citizens often cause with their unjustified calls, that police and regulatory authorities are distracted from their real duties.
The basis for the penal law in Germany is the German Strafgesetzbuch (StGB) – in English: Criminal Code.
The Criminal Code contains two sections, which address sexual delicts:
Acts of exhibitionism
(1) A man who vexes another person by committing an act of exhibitionism incurs a penalty of imprisonment for a term not exceeding one year or a fine.
(2) The offence is prosecuted only upon request, unless the prosecuting authority deems there to be a special public interest in prosecution which calls for ex officio intervention.
(3) The court may even suspend a sentence of imprisonment on probation if there is reason to believe that the offender will only cease to commit acts of exhibitionism after lengthy medical treatment.
(4) Subsection (3) also applies if a man or a woman is convicted of an act of exhibitionism
1. under another provision which imposes a maximum sentence of imprisonment not exceeding one year or a fine or
2. under section 174 (3) no. 1 or section 176 (4) no. 1.
Cit. of a statement by a lawyer of penal law
(Translated cit. of a statement in an article "Der Begriff der exhibitionistischen Handlung" [en: "The term of an exhibitionistic deed"] in strafrechtsblogger.de)
Translated cit. of a statement by a lawyer of penal law:
»Definition: An exhibitionistic deed requires exposing the penis to another person.
The penis does not need to be erect. If, however, only an imitation of the phallus is shown, the element of the offence is not fulfilled. The deed also requires a subjective component, in which the offender is sexually excited, aggravates his sexual exitement, or gets his sexual satisfaction by the deed or by observation of reaction from others. However, it is not necessary to achieve real sexual satisfaction.
Furthermore, offender and victim must be present at the same time. Consequently, it is not sufficient, when recorded images or films of the deed are shown. On the other hand, deeds, that are transmitted over the Internet in front of a camera are sufficient (controversial in the literature).
On the other hand, an exposure for provocation, for urination, or even as mere demonstration of a nude lifestyle, as in the case of nude joggers, is not an exhibitionistic act. Furthermore, it is generally not punishable, if the offender merely considers the possibility of being observed by another person.«
Source (in German): Rechtsanwalt Steffen Dietrich, Anwalt für Strafrecht aus Berlin
Judgment as to section 183 "Exhibitionism", Bavaria [16 June 1998]
(Translated cit. of a statement in an article "Exhibitionismus" in de.wikipedia.org)
»According to a judgment of the Bayerisches Oberlandesgericht [en: Bavarian Higher Regional Court] in 1998 (BayObLG (2. Strafsenat), Urteil vom 16. Juni 1998 – 2 St RR 86/98, NJW 1999, 72), the element of an offence of exhibitionism is only fulfilled, if the disrobement serves for sexual satisfaction. Nudity and therefore nude sport in the public alone is therefore not punishable in Germany.«
Source (in German): de.wikipedia.org
Also, there is an article "Exhibitionism" written in English in en.wikipedia.org, but it is not a translation of the German one, which addresses especially the situation in Germany!
Causing public nuisance
Whoever performs sexual acts in public and thereby intentionally or knowingly offends common decency incurs a penalty of imprisonment for a term not exceeding one year or a fine, unless the act is liable to a penalty under section 183.
The term public disturbance is thus expressly bound to a sexual act, not to mere nudity.
Note on some neighboring countries: This restriction of the term "public disturbance" to sexually motivated offences in the German Criminal Code does not apply in some of our neighboring countries. In Switzerland and Luxembourg, for example, "disturbance of sleep by bellowing drunks" is also declared as public disturbance.