All three sports represented in The Escape from Alcatraz give a unique experience to the triathlon, but I would argue that swimming is by far the most special and the reason why this triathlon exists.
All 2000 swimmers board "the Hornblower," the boat that's both a shuttle and the starting line for the race. Warming up is apparently for sissies, because the participants jump from the boat as the start signal is sounded. Watch the video above to see this is in action.
Then comes the 2500 meter long swim. This swim is dreaded for several reasons.
First of all, because it is long. Usually when a swim is this long, both biking and running tends to be longer as well. This is not the case, especially not after the course changed in 1993, when both biking and running was made shorter to fit within the San Francisco borders. If you are a good swimmer, then you'll have a better shot at winning this race than any other.
Secondly, the water is freezing. It is usually from 12° to 16° C, which is kinda normal for me when training during the summer in Norway, but still pretty cold. Wet suits are therefore mandatory, at least in my opinion..
The third reason is the strong current. As far as I have understood they try to put the start of the swim at a particular time when there is less current, but the smaller current will still inflicts greatly on the direction you'll have to swim in order not to end up swimming against it at the end. The lifeguards that follow the contestants have the authority to pick up and move a swimmer back into the correct position without having them disqualified.
The strong current also means that as long as you swim correctly in the beginning the last meters will be swimming with the current. The cap for the swimming leg is one hour and the contestants that can't finish within the time limit gets placed close to the shore so they can continue the race.
When they first started this triathlon many people did it without wet suits, and they got so cold they fell off their bikes later in the race. For this reason they inserted a 1 km warm up run from the time you get out of the water until you get to the bike. Many do this run barefoot while still being in their wet suits, but there is also a possibility to leave shoes ready.
For more information check out the video below.