In 1923 she embarked on the crossing of the River Plate.
Until then, nine attempts to cross the River Plate had been made.
But these attempts, by swimmers Enrique Tirabocchi, Luis Garramendy, Elio Pérez, Romero Maciel and Vito Dumas, had failed.
Of these, Dumas had been the one who resisted longest in the water (25 hours and 17 minutes), while Maciel was the swimmer who covered the longest distance, abandoning his attempt when he was only 3 kilometers (1.9 miles) short of his point of destination.

Lilian Harrison started her crossing on December 21, 1923, from the port of  Colonia, in Uruguay, at 9:28 in the morning.
During the first stretch, she was accompanied by uruguayan swimmers Caracciolo and Graneri, and had to struggle during three hours against the current pushing them back toward the uruguayan coast.
Then she headed toward the south, accompanied by Tiraboschi and Wernotri.

At 15:30 she drank some orange juice, at 17 a coffee, and at 18:30 a lump of sugar.
As night fell, her team realized that they had not brought reflectors, an error that could have boomed the crossing but that was partially compensated by the moon light,
From 1 o'clock until 4 a.m. she swam alone.
At 4:30 the argentine coast was seen from the boats that were accompanying her.
At that moment she was about to abandon, given that she was exhausted.
But she managed to continue when she was told that she was 5 kilometers (3.1 miles) away from her goal.

She touched shore on the argentine side of the River Plate at 9:47 in the morning, on the Playa Colorada, close to the Punta Lara.
She had covered 48 kilometers (29.8 miles) in 24 hours and 19 minutes.
In 1923 she embarked on the crossing of the River Plate. Until then, nine attempts to cross the River Plate had been made. But these attempts, by swimmers Enrique Tirabocchi, Luis Garramendy, Elio Pérez, Romero Maciel and Vito Dumas, had failed. Of these, Dumas had been the one who resisted longest in the water (25 hours and 17 minutes), while Maciel was the swimmer who covered the longest distance, abandoning his attempt when he was only 3 kilometers (1.9 miles) short of his point of destination.
Lilian Harrison started her crossing on December 21, 1923, from the port of  Colonia, in Uruguay, at 9:28 in the morning. During the first stretch, she was accompanied by uruguayan swimmers Caracciolo and Graneri, and had to struggle during three hours against the current pushing them back toward the uruguayan coast. Then she headed toward the south, accompanied by Tiraboschi and Wernotri. 
At 15:30 she drank some orange juice, at 17 a coffee, and at 18:30 a lump of sugar. As night fell, her team realized that they had not brought reflectors, an error that could have boomed the crossing but that was partially compensated by the moon light,
From 1 o'clock until 4 a.m. she swam alone. At 4:30 the argentine coast was seen from the boats that were accompanying her. At that moment she was about to abandon, given that she was exhausted. But she managed to continue when she was told that she was 5 kilometers (3.1 miles) away from her goal.
She touched shore on the argentine side of the River Plate at 9:47 in the morning, on the Playa Colorada, close to the Punta Lara. She had covered 48 kilometers (29.8 miles) in 24 hours and 19 minutes.
Lilian Harrison