your problem with a conventional sub is always range - especially submerged
For the Collins boats Wiki gives
Range
- 11,500 nautical miles (21,300 km; 13,200 mi) at 10 knots (19 km/h; 12 mph) surfaced
- 9,000 nmi (17,000 km; 10,000 mi) at 10 kn (19 km/h; 12 mph) periscope
- 480 nmi (890 km; 550 mi) at 4 kn (7.4 km/h; 4.6 mph) submerged
Endurance 70 days
A Los Angleses is given as
Speed
- Surfaced: 20 knots (37 km/h; 23 mph)
- Submerged: Over 25 knots (46 km/h; 29 mph), official;[3] 33+ knots, reported[4][5]
Range Refueling required after 30 years
[
Endurance 90 days
For Australia - it's 2500 kms just to reach the southern side of Indonesia from Fremantle. That's 100 hours/4days submerged for an SSN but 10 days on the surface for a Collins.