About the AUD/BHD rate
The AUD/BHD rate is how many BHD one Australian dollar buys. It moves constantly with interest-rate expectations, commodity prices and global risk sentiment - see what moves the rate. Tradergy shows the mid-market reference rate and does not forecast where it’s heading. For the 52-week highs and lows and a daily table, see the AUD/BHD rate history.
The other directions of this rate: the reverse rate, BHD → AUD, is on the receiving Bahraini dinar view, and sending Australian dollars to Bahrain is covered on the AUD → BHD transfer page. Every AUD pair sits on the convert hub, and to work in more than one currency at once there is the currency converter.
The other currency in the till
Bahraini law is short and unambiguous on this. Article 14 of the Central Bank of Bahrain and Financial Institutions Law, issued as Decree No 64 of 2006, provides that currency notes issued by the Central Bank are legal tender for their full value, and that coins are legal tender for their nominal value up to five Bahraini dinars. No other currency is named anywhere in that provision.
Practice is a separate question, and Bahrain answers it in a different document. The Bahrain Tourism and Exhibitions Authority, the Kingdom's own tourism body, tells visitors that Saudi riyals are accepted at all points of sale in Bahrain, with the exception of the 500 riyal note, which it says is taken only at major supermarkets, airports and electronics shops. That is a statement about what tills do, published by an official body, and it is not the same claim as legal tender.
These two facts are frequently collapsed into one, and they are different. A currency can be accepted everywhere without being legal tender, which means a merchant may take it and is under no obligation to. The Central Bank of Bahrain's own currency pages describe the dinar note series and make no mention of any foreign currency at all, which is what a central bank describing its own issue would be expected to do.
The exception the tourism authority carves out is the informative detail. A 500 riyal note is the largest denomination in the Saudi series, and the places it says will still take one are supermarkets, airports and electronics retailers: businesses with a cash office, a float and a reason to handle large notes. What the tourism authority describes is therefore acceptance that varies by denomination and by the kind of business behind the counter.
Sources: Central Bank of Bahrain and Financial Institutions Law, Decree No 64 of 2006, Article 14 (Currency Issue) · Bahrain Tourism and Exhibitions Authority, currency and payments · Central Bank of Bahrain, Currency Issue