I think, Google translation as "elemental force" is correct.
'стихия' means the active and hostile actions of nature. For example, strong wind and rain, storm at the sea, big forest fire, etc. All of these can be called 'стихия'.
Also, the 'стихия' word can be used for unplanned human actions: 'стихия' of the love - unplanned, fired emotion.
It is also worth noting that the expression "elemental force, which tourists were not able to overcome" in this context is unclear and rarely used in official documents.
In the context of this document, it sounds incomprehensible and mysterious, including for Russian-speaking readers.