| Length | River | % Correct |
|---|---|---|
| 360 km | Shannon | 96%
|
| 132 km | Liffey | 87%
|
| 89 km | Lee | 67%
|
| 192 km | Barrow | 60%
|
| 184 km | Suir | 57%
|
| 86 km | Lagan | 55%
|
| 159 km | Bann | 54%
|
| 68 km | Blackwater (Leinster) | 54%
|
| 168 km | Blackwater (Munster) | 54%
|
| 92 km | Blackwater (Ulster) | 54%
|
| 140 km | Nore | 53%
|
| 113 km | Boyne | 52%
|
| 129 km | Foyle | 50%
|
| 129 km | Erne | 38%
|
| 101 km | Moy | 33%
|
| 117 km | Slaney | 33%
|
| 133 km | Suck | 28%
|
| 72 km | Bandon | 24%
|
| 62.8 k | Finn | 21%
|
| 58.4 k | Fergus | 17%
|
| 89 km | Inny | 14%
|
| 79 km | Brosna | 13%
|
| 93 km | Clare | 13%
|
| 60.4 k | Dee | 11%
|
| 74 km | Feale | 11%
|
| 64 km | Boyle | 7%
|
| 61.2 k | Fane | 6%
|
| 76 km | Laune | 6%
|
| 62 km | Maigue | 6%
|
| 66.8 k | Annalee | 5%
|
| 64 km | Bride | 5%
|
| 63.2 k | Deel | 5%
|
| 55.9 k | Glyde | 5%
|
| 55.9 k | Mulkear | 4%
|
| 62.8 k | Robe | 4%
|
| 57.6 k | Little Brosna | 3%
|
| 60.8 k | Ballisodare | 2%
|